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  1.  
  2.  
  3. This is a lazy list I'm putting together because I was asked to.
  4. It's going to be organized in a Q&A fashion, with some basic info on what each study is and the source's name since there might be dead links.
  5. As you can see, I probably have well over a hundred studies in here. Each one I have read, but I can't remember the exact results of each one; so if you want to know the exact numbers, read the sources for yourself. The sources that have the results in the descriptions of the studies are either because I remember that study well enough to name it off the top of my head or because for some reason I wrote it down when noting what study was what. Or, I might have left the abstract as the description because I felt that the abstract was accurate in describing the actual study itself (do not just read the abstract of each study, as the abstracts can be misleading or have false information a about the actual paper).
  6. That being said, me going back and re-reading each study to name each specific result and correlation coefficient would take days as I collected these sources over the years, and I don't want to invest that much time back into them. If you got a got question, let me know.
  7.  
  8. - J
  9.  
  10. What does IQ measure?
  11. Intelligence quotient (IQ) is meant to measure intelligence, with the majority of IQ tests being developed for measuring intelligence in humans, but several IQ tests have been made and used to measure intelligence in other species (for example, see Differences in cognitive abilities among primates are concentrated on G: Phenotypic and phylogenetic comparisons with two meta-analytical databases by Fernandes and Woodley, which found a general intelligence factor among primates).
  12.  
  13. What is the validity of IQ?
  14. Validity in psychometrics (psychometrics being the study of the science measuring mental capacities and processes) refers to a test's ability to measure what it is suppose to measure. As IQ is set out to measure intelligence, one way we are able to validate its ability to do so is to ask what IQ predicts and how well in what we would imagine are things that are related to intelligence.
  15.  
  16. So what does IQ predict that could be related to intelligence and how well?
  17.  
  18. IQ is able to predict socioeconomic status (income, occupation and education) better than other predictors such as parental educational attainment, parental occupation, and academic performance; IQ correlates to income at .23; .45 with occupation; and .56 with education.
  19. Source: Strenze, t. (2007). intelligence and socioeconomic success: a meta-analytic http://www.sciencedirect.com/science/article/pii/S0160289606001127
  20.  
  21. Standardized measures of intelligence, ability, or achievement are all measures of acquired knowledge and skill and have consistent relationships with multiple facets of success in life, including academic and job performance. Five persistent beliefs about ability tests have developed, including: (a) that there is no relationship with important outcomes like creativity or leadership, (b) that there is predictive bias, (c) that there is a lack of predictive independence from socioeconomic status, (d) that there are thresholds beyond which scores cease to matter, and (e) that other characteristics, like personality, matter as well. We present the evidence and conclude that of these five beliefs, only the importance of personality is a fact; the other four are fiction.
  22. Source: Fact and Fiction in Cognitive Ability Testing for Admissions and Hiring Decisions, Nathan R. Kuncel, Sarah A. Hezlett http://journals.sagepub.com/doi/abs/10.1177/0963721410389459
  23.  
  24. The predictive validity of cognitive ability tests: A UK meta-analysis
  25. (job performance predicts IQ: uk meta analysis)
  26. Source: The predictive validity of cognitive ability tests: A UK meta‐analysis, Cristina Bertua http://onlinelibrary.wiley.com/doi/10.1348/096317905X26994/abstract
  27.  
  28. "A one-point increase in IQ is associated with a 4% increase in welfare growth for the average country. Our results support the view that national IQ is an important determinant of cross-country differences in economic activity and welfare."
  29. Source: New estimates on the relationship between IQ, economic growth and welfare by R.W.Hafer
  30. http://www.sciencedirect.com/science/article/pii/S016028961630318X
  31.  
  32. "They found that intelligence made a difference in gross domestic product. For each one-point increase in a country’s average IQ, the per capita GDP was $229 higher. It made an even bigger difference if the smartest 5 percent of the population got smarter; for every additional IQ point in that group, a country’s per capita GDP was $468 higher."
  33. Source: Are the Wealthiest Countries the Smartest Countries? by Heiner Rindermann http://www.psychologicalscience.org/news/releases/are-the-wealthiest-countries-the-smartest-countries.html#.WQIZG8tlDqA
  34.  
  35. Cognitive Performance and Labour Market Outcomes
  36. (Interesting part is that blacks and Hispanics have better income returns for their IQ level...)
  37. Source: Cognitive performance and labour market outcomes, Dajun Lin https://www.sciencedirect.com/science/article/pii/S0927537117303329
  38.  
  39. The relationship between cognitive-ability saturation and subgroup mean differences across predictors of job performance. Spearman's hypothesis
  40. Source: The relationship between cognitive-ability saturation and subgroup mean differences across predictors of job performance, Dahlke, Jeffrey A http://psycnet.apa.org/doiLanding?doi=10.1037%2Fapl0000234
  41.  
  42. Types of intelligence predict likelihood to get married and stay married: Large-scale empirical evidence for evolutionary theory (small r (=.07 and .05).
  43. Source: Types of intelligence predict likelihood to get married and stay married: Large-scale empirical evidence for evolutionary theory, Jaakko Aspara http://www.sciencedirect.com/science/article/pii/S0191886917305780
  44.  
  45. General intelligence and educational achievement (r = .81)
  46. Source: Intelligence and educational achievement, Ian J.Deary http://www.sciencedirect.com/science/article/pii/S0160289606000171
  47.  
  48. IQ predicts likelihood of being an inventor
  49. Source: The Social Origins of Inventors, Philippe Aghion, Ufuk Akcigit, Ari Hyytinen, Otto Toivanen http://www.nber.org/papers/w24110
  50.  
  51. G correlates to video games at .93
  52. Source: Can we reliably measure the general factor of intelligence (g) through commercial video games? Yes, we can! by M.Ángeles Quirogaa
  53. http://www.sciencedirect.com/science/article/pii/S016028961500104X
  54.  
  55. More school grades and IQ (r = .54)
  56. Source: Intelligence and school grades: A meta-analysis, Bettina Roth http://www.sciencedirect.com/science/article/pii/S0160289615001269
  57.  
  58. g accounts for achievement variances, medium variance is .46
  59. Source: Incremental validity of the WJ III COG: Limited predictive effects beyond the GIA-E., McGill RJ https://www.ncbi.nlm.nih.gov/pubmed/25313719
  60.  
  61. Iq not personality predicts success
  62. Source: IQ, not personality, key to success: study By Press Trust of India http://wap.business-standard.com/article-amp/pti-stories/iq-not-personality-key-to-success-study-118032100825_1.html
  63.  
  64. IQ predicts crime:
  65. Sources:
  66. Is the Association between General Cognitive Ability and Violent Crime Caused by Family-Level Confounders? Thomas Frisell, Yudi Pawitan, Niklas Långström http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0041783
  67.  
  68. Intelligence and criminal behavior in a total birth cohort: An examination of functional form, dimensions of intelligence, and the nature of offending, Joseph A.Schwartz
  69. http://www.sciencedirect.com/science/article/pii/S016028961500077X
  70.  
  71. National IQs predict educational attainment in math, reading and science across 56 nations (PISA scores), Richard Lynn
  72. https://www.researchgate.net/publication/223935140_National_IQs_predict_educational_attainment_in_math_reading_and_science_across_56_nations
  73.  
  74. IQ correlates to Human Development Index at .85 (Source: Human Development Related to Human Diversity(National IQ)
  75. Tatu Vanhanen (Co-leader) Visiting Researcher, Department of Political Science, University of Helsinki, Finland).
  76. https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.scj.go.jp/ja/int/kaisai/jizoku/dynamism-asia/program/pdf/21_tatu-vanhanen.pdf&ved=0ahUKEwiS1vqgmv_WAhXjrlQKHVrhCccQFgglMAA&usg=AOvVaw2F7m3Y6Wny-qHg-CTweUZF
  77.  
  78. Noah (2016)
  79. Cross-regional correlations between average IQ and socio-economic development have been reported for many different countries. This paper analyses data on average IQ and a range of socio-economic variables at the local authority level in the UK. Local authorities are administrative bodies in local government; there are over 400 in the UK, and they contain anywhere from tens of thousands to more than a million people. The paper finds that local authority IQ is positively related to indicators of health, socio-economic status and tertiary industrial activity; and is negatively related to indicators of disability, unemployment and single parenthood. A general socio-economic factor is correlated with local authority IQ at r = .56. This correlation increases to r = .65 when correcting for measurement error in the estimates of IQ.
  80. http://www.sciencedirect.com/science/article/pii/S0160289616300411
  81.  
  82. Carl (2015)
  83. Cross-regional correlations between average IQ and socioeconomic development have been documented in many different countries. This paper presents new IQ estimates for the twelve regions of the UK. The paper provides evidence for the validity of the regional IQs by showing that IQ estimates for UK nations (England, Scotland, Wales and Northern Ireland) derived from the same data are strongly correlated with national PISA scores (r=0.99). It finds that regional IQ is positively related to income, longevity and technological accomplishment; and is negatively related to poverty, deprivation and unemployment. A general factor of socioeconomic development is correlated with regional IQ at r=0.72.
  84. https://www.ncbi.nlm.nih.gov/pubmed/26088751
  85.  
  86. What is the reliability of IQ?
  87. Depends on the test and the time it was made compared to the time that the participants are taking it, but highly reliable generally; for example Gary L. Canivez found the long term stability of WISC III to be .91 http://psycnet.apa.org/record/1998-10845-010
  88.  
  89. Is IQ heritable? If so, how much?
  90. Yes, IQ is heritable with the heritability of IQ being around .8 within adulthood (around 24 years old).
  91.  
  92. Intelligence is 20% heritable in infancy. 80% in adulthood:
  93. Source: Genetics and intelligence differences: five special findings, R Plomin http://www.nature.com/mp/journal/v20/n1/full/mp2014105a.html
  94.  
  95. IQ .80 heritable and by what age:
  96. Source: Age-Related Changes in Heritability
  97. of Behavioral Phenotypes Over Adolescence
  98. and Young Adulthood: A Meta-Analysis, Sarah E. Bergen https://docs.google.com/file/d/0B0VDoaXaIou8QzBKdEw2QVZsVUU/edit
  99.  
  100. IQ largely genetic:
  101. Source: IQ is in the genes: How parents raise us has no impact on how smart we become, a new study finds, SHARON OOSTHOEK https://www.sciencenewsforstudents.org/article/iq-genes
  102.  
  103. g is .86 heritable, with unique environment accounting for .14 of the variance:
  104. Source: Genetic and Environmental Influences of General Cognitive Ability: Is g a valid latent construct? Matthew S. Panizzon https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4002017/
  105.  
  106. Shared environment falls to .0 in adulthood in regards to IQ and IQ around .8 heritable.
  107. Genetic and environmental influences on human psychological differences, Thomas J. Bouchard Jr http://onlinelibrary.wiley.com/doi/10.1002/neu.10160/abstract
  108.  
  109. Shared environment falling to .0 and IQ around .8 heritable.
  110. Genetic Influence on Human Psychological Traits A Survey Thomas J. Bouchard, Jr. University of Minnesota, Minneapolis
  111. http://www18.homepage.villanova.edu/diego.fernandezduque/Teaching/PhysiologicalPsychology/zCurrDir4200/CurrDirGeneticsTraits.pdf
  112.  
  113. Heritability of general cognitive ability in these twins was much higher (about 80%) than estimates typically found earlier in life (about 50%). http://journals.sagepub.com/doi/abs/10.1111/j.1467-9280.1992.tb00045.x
  114.  
  115. Shared environment not statistically significant when modeled as unique environment between MZ twins and the heritability of IQ.
  116. Source: A closer look at the role of parenting-related influences on verbal intelligence over the life course: Results from an adoption-based research design, Kevin M.Beaver
  117. http://www.sciencedirect.com/science/article/pii/S0160289614000889
  118.  
  119. IQ reaches .8 heritability in older age:
  120. Source: The Wilson Effect: the increase in heritability of IQ with age, Bouchard TJ https://www.ncbi.nlm.nih.gov/pubmed/23919982"
  121.  
  122. When does socioeconomic status (SES) moderate the heritability of IQ? No evidence for g × SES interaction for IQ in a representative sample of 1176 Australian adolescent twin pairs
  123. http://www.sciencedirect.com/science/article/pii/S0160289616300629
  124.  
  125. Shared environment in adoptees falls to .0 in adulthood (Robert Plomin 2008, Behavioral Genetics, Pg. 166, chapter 8)
  126. https://books.google.com/books?id=Q2wrobk-HwMC&pg=PA166&lpg=PA166&dq=adoption+iq+adulthood&source=bl&ots=jBYuqDNgg1&sig=XbK29HXgI5XvGo6_L2J-cPSsTaQ&hl=en&sa=X&ved=2ahUKEwjDwLCslozYAhVN9mMKHQJOAGI4ChDoATAAegQIChAB#v=onepage&q=adoption%20iq%20adulthood&f=false
  127.  
  128. Adopted children resemble their adoptive parents slightly in early childhood but not at all in middle childhood or adolescence
  129. Source: Nature, Nurture, and Cognitive Development from 1 to 16 Years: A Parent-Offspring Adoption Study, Robert Plomin http://journals.sagepub.com/doi/abs/10.1111/j.1467-9280.1997.tb00458.x
  130.  
  131. Is there genetic data showing that IQ is heritable?
  132. Yes; Genome-Wide Association Studies (GWAS's) have validated twin studies on the heritability of IQ. (Note: GWAS estimates of heritability are much lower than twin studies due to GWAS's not being able to measure non-additive genetic affects; a.k.a., GWAS's are known to have what's called "missing heritability" as they are only able to measure additive genetic effects and can not measure non-additive genetic effects in their current state.)
  133.  
  134. On missing heritablity: by capturing these additional genetic effects our models closely approximate the heritability estimates from twin studies for intelligence and education
  135. Source: Genomic analysis of family data reveals additional genetic effects on intelligence and personality, William David Hill https://www.biorxiv.org/content/early/2017/06/05/106203
  136.  
  137. Intelligence .5 heritable using SNPs (2018)
  138. Source: Genomic analysis of family data reveals additional genetic effects on intelligence and personality, W. David Hill https://www.nature.com/articles/s41380-017-0005-1
  139.  
  140. It is now possible to test these hypotheses using DNA alone. From 1.7 million DNA markers and g scores at ages 7 and 12 on 2875 children, the DNA genetic correlation from age 7 to 12 was 0.73, highly similar to the genetic correlation of 0.75 estimated from 6702 pairs of twins from the same sample. DNA-estimated heritabilities increased from 0.26 at age 7 to 0.45 at age 12; twin-estimated heritabilities also increased from 0.35 to 0.48. These DNA results confirm the results of twin studies indicating strong genetic stability but increasing heritability for g, despite mean changes in brain structure and function from childhood to adolescence.
  141. Source: DNA evidence for strong genetic stability and increasing heritability of intelligence from age 7 to 12, M Trzaskowski
  142. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3932402/
  143.  
  144. We apply MTAG to three large GWAS: Sniekers et al (2017) on intelligence, Okbay et al. (2016) on Educational attainment, and Hill et al. (2016) on household income. By combining these three samples our functional sample size increased from 78 308 participants to 147 194. We found 107 independent loci associated with intelligence, implicating 233 genes, using both SNP-based and gene-based GWAS.
  145. Source: A combined analysis of genetically correlated traits identifies 107 loci associated with intelligence, William D. Hill
  146. http://www.biorxiv.org/content/early/2017/07/07/160291
  147.  
  148. Does IQ heritability increase with age?
  149. Yes, and this is known as either "gene amplification", "increasing heritability" and/or "The Wilson Effect"; which leads IQ to being heritable around .2 in childhood (ages: 5-10), around .4 to .6 in adolescence up to young adulthood (ages: 10-18), and finally pushing around .8 in adulthood (age: around 24).
  150.  
  151. Ronald Wilson presented the first clear and compelling evidence that the heritability of IQ increases with age. We propose to call the phenomenon 'The Wilson Effect' and we document the effect diagrammatically with key twin and adoption studies, including twins reared apart, that have been carried out at various ages and in a large number of different settings. The results show that the heritability of IQ reaches an asymptote at about 0.80 at 18-20 years of age and continuing at that level well into adulthood. In the aggregate, the studies also confirm that shared environmental influence decreases across age, approximating about 0.10 at 18-20 years of age and continuing at that level into adulthood. These conclusions apply to the Westernized industrial democracies in which most of the studies have been carried out.
  152. Source: The Wilson Effect: the increase in heritability of IQ with age, Bouchard TJ
  153. https://www.ncbi.nlm.nih.gov/pubmed/23919982"
  154.  
  155. Genetic amplification:
  156. Source: Genetics and intelligence differences: five special findings, R Plomin http://www.nature.com/mp/journal/v20/n1/full/mp2014105a.html
  157.  
  158. Shared environment in adoptees falls to .0 in adulthood
  159. Source: Robert Plomin 2008, Behavioral Genetics, Pg. 166, chapter 8
  160. https://books.google.com/books?id=Q2wrobk-HwMC&pg=PA166&lpg=PA166&dq=adoption+iq+adulthood&source=bl&ots=jBYuqDNgg1&sig=XbK29HXgI5XvGo6_L2J-cPSsTaQ&hl=en&sa=X&ved=2ahUKEwjDwLCslozYAhVN9mMKHQJOAGI4ChDoATAAegQIChAB#v=onepage&q=adoption%20iq%20adulthood&f=false
  161.  
  162. IQ .80 heritable and by what age:
  163. Source: Age-Related Changes in Heritability
  164. of Behavioral Phenotypes Over Adolescence
  165. and Young Adulthood: A Meta-Analysis, Sarah E. Bergen https://docs.google.com/file/d/0B0VDoaXaIou8QzBKdEw2QVZsVUU/edit
  166.  
  167. Adopted children resemble their adoptive parents slightly in early childhood but not at all in middle childhood or adolescence
  168. Source: Nature, Nurture, and Cognitive Development from 1 to 16 Years: A Parent-Offspring Adoption Study, Robert Plomin http://journals.sagepub.com/doi/abs/10.1111/j.1467-9280.1997.tb00458.x
  169.  
  170. It is now possible to test these hypotheses using DNA alone. From 1.7 million DNA markers and g scores at ages 7 and 12 on 2875 children, the DNA genetic correlation from age 7 to 12 was 0.73, highly similar to the genetic correlation of 0.75 estimated from 6702 pairs of twins from the same sample. DNA-estimated heritabilities increased from 0.26 at age 7 to 0.45 at age 12; twin-estimated heritabilities also increased from 0.35 to 0.48. These DNA results confirm the results of twin studies indicating strong genetic stability but increasing heritability for g, despite mean changes in brain structure and function from childhood to adolescence.
  171. Source: DNA evidence for strong genetic stability and increasing heritability of intelligence from age 7 to 12, M Trzaskowski
  172. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3932402/
  173.  
  174. What effect does shared environment have on IQ?
  175. Shared environment can possibly have a huge effect on IQ. However, usually most studies show that by adulthood, shared environmental effects drop to .0 of the variance in IQ: meaning that by adulthood, shared environment accounts for .0 of the variance in IQ in the general population (within the U.S. and other industrialized nations).
  176. (See sections Is IQ heritable? If so, how much?; Does IQ heritability increase with age?; and What environmental effects affect g? too for related readings.)
  177.  
  178. g is .86 heritable, with unique environment accounting for .14 of the variance:
  179. Source: Genetic and Environmental Influences of General Cognitive Ability: Is g a valid latent construct? Matthew S. Panizzon https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4002017/
  180.  
  181. Shared environment falls to .0 in adulthood in regards to IQ and IQ around .8 heritable.
  182. Genetic and environmental influences on human psychological differences, Thomas J. Bouchard Jr http://onlinelibrary.wiley.com/doi/10.1002/neu.10160/abstract
  183.  
  184. Shared environment falling to .0 and IQ around .8 heritable.
  185. Genetic Influence on Human Psychological Traits A Survey Thomas J. Bouchard, Jr. University of Minnesota, Minneapolis
  186. http://www18.homepage.villanova.edu/diego.fernandezduque/Teaching/PhysiologicalPsychology/zCurrDir4200/CurrDirGeneticsTraits.pdf
  187.  
  188. Shared environment not statistically significant when modeled as unique environment between MZ twins.
  189. Source: A closer look at the role of parenting-related influences on verbal intelligence over the life course: Results from an adoption-based research design, Kevin M.Beaver
  190. http://www.sciencedirect.com/science/article/pii/S0160289614000889
  191.  
  192. IQ reaches .8 heritability in older age:
  193. Source: The Wilson Effect: the increase in heritability of IQ with age, Bouchard TJ https://www.ncbi.nlm.nih.gov/pubmed/23919982"
  194.  
  195. Shared environment in adoptees falls to .0 in adulthood (Robert Plomin 2008, Behavioral Genetics, Pg. 166, chapter 8)
  196. https://books.google.com/books?id=Q2wrobk-HwMC&pg=PA166&lpg=PA166&dq=adoption+iq+adulthood&source=bl&ots=jBYuqDNgg1&sig=XbK29HXgI5XvGo6_L2J-cPSsTaQ&hl=en&sa=X&ved=2ahUKEwjDwLCslozYAhVN9mMKHQJOAGI4ChDoATAAegQIChAB#v=onepage&q=adoption%20iq%20adulthood&f=false
  197.  
  198. Adopted children resemble their adoptive parents slightly in early childhood but not at all in middle childhood or adolescence
  199. Source: Nature, Nurture, and Cognitive Development from 1 to 16 Years: A Parent-Offspring Adoption Study, Robert Plomin http://journals.sagepub.com/doi/abs/10.1111/j.1467-9280.1997.tb00458.x
  200.  
  201. There is a previously well-established relationship between socioeconomic status and cognitive ability. By having access to repeated measures of cognitive data across the second part of the life span, we were able not only to study the influence of childhood social class on mean-level cognitive performance, but also on change over time. Using reared-apart monozygotic and dizygotic twins and a control sample of twins reared together, we studied the effects of childhood socioeconomic environment on cognition in later life. We found an association between childhood social class and mean levels of cognitive performance, but not longitudinal trajectories of change. When controlling for genetic influences, there was no association of childhood social class and cognitive performance late in life.
  202. Source: Childhood social class and cognitive aging in the Swedish Adoption/Twin Study of Aging by Malin Ericsson https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5502597/
  203.  
  204. What is the g-factor?
  205. The g-factor is the general intelligence factor, also known as just g or general intelligence.
  206. For readings on what the g-factor is, see sources below:
  207.  
  208. Psychometric g: Definition and Substantiation by Arthur R. Jensen:
  209. http://arthurjensen.net/wp-content/uploads/2014/06/Psychometric-g-Definition-and-Substantiation-2002-by-Arthur-Robert-Jensen.pdf
  210.  
  211. The g Factor: The Science of Mental Ability by Arthur Jensen:
  212. http://emilkirkegaard.dk/en/wp-content/uploads/The-g-factor-the-science-of-mental-ability-Arthur-R.-Jensen.pdf
  213.  
  214. Spearman’s g and the problem of educational equality (see pg. 170): http://arthurjensen.net/wp-content/uploads/2014/06/Spearmans-g-and-the-Problem-of-Educational-Equality-1991-by-Arthur-Robert-Jensen.pdf
  215.  
  216. The g beyond factor analysis by Arthur Jensen (see pg. 90, section FACTOR ANALYSIS AND THE HIGHEST ORDER FACTOR): http://arthurjensen.net/wp-content/uploads/2014/06/4.-The-g-Beyond-Factor-Analysis.pdf
  217.  
  218. The General Intelligence Factor by Linda S. Gottfredson: http://www.udel.edu/educ/gottfredson/reprints/1998generalintelligencefactor.pdf
  219.  
  220. Logical Fallacies Used to Dismiss the Evidence on Intelligence Testing, Linda S. Gottfredson: http://www.udel.edu/educ/gottfredson/reprints/2009fallacies.html
  221.  
  222. What is a test's g-loading?
  223. A test's g-loading is the ablity of that test to measure g; i.e., the more a test's subtests correlate and predict one another, the more correlated with g it is; and the more a IQ test correlate with g, the more g-loaded that IQ test or IQ test proxy is.
  224.  
  225. How well do IQ tests measure g?
  226. Some IQ tests are better at measuring g than other IQ tests and some tests measure g at a different amount. For example, the WISC-IV has a g-loading of .94 while the DAS-II GCA has a g-loading of .92, and while the WISC-III only has a g-loading of .88; another example is of different IQ tests having different abilities to measure g is the Ravens Progressive Matrices tests, which is estimated to have a g-loading of only .65 to .76.
  227.  
  228. https://www.researchgate.net/publication/263814084_IQs_are_very_strong_but_imperfect_indicators_of_psychometric_g_Results_from_joint_confirmatory_factor_analysis
  229.  
  230. https://www.researchgate.net/publication/282711615_Raven's_is_not_a_pure_measure_of_general_intelligence_Implications_for_g_factor_theory_and_the_brief_measurement_of_g
  231.  
  232. Do different subtests have different g-loadings?
  233. Yes they do. Some subtests and specific domain intelligences are better at measure g and are more g-loaded than others.
  234.  
  235. For example, the WISC–IV subtests measure g at...
  236. .83 for Vocabulary
  237. .81 for Information
  238. .77 for Arithmetic
  239. .66 for Picture Completion
  240. .57 for Digit Span
  241. http://alpha.fdu.edu/psychology/wisciv_gloadings.htm
  242.  
  243. How do we factor out g in a test?
  244. g is extracted from the test by correlating to each subtest to each other. The higher they correlate, the higher the test's g-loading. This is usually done by a factor analysis, but can also be done using other methods such as a principal component analysis and Linear Structural Relations.
  245.  
  246. For a good paper that looks at extraction of g using different models, read Arthur Jensen's What is good g?: http://www.sciencedirect.com/science/article/pii/0160289694900299
  247.  
  248. What is intelligence that isn't g?
  249. There are competing thoeries of intelligence (see Spearman's 2 domain intelligence theory; Carroll's hierarchy of intelligence; and Gardner's Theory of multiple intelligences for example) but generally intelligence that isn't g is called specific intelligence or domain specific intelligence. It's cognitive abilities or amounts of cognitive abilities that do not generalize (correlate) to other cognitive abilities. For example, Verbal IQ (once g is extracted) is a specific domain intelligence as It's specifically within the domain of verbal ability. This is contrasted to general intelligence, which is intelligence that expands to all greater domains of intelligence via correlating with one another. (See question "What is the g-factor?" for further readings as well.)
  250.  
  251. Are some subtests more heritable than others and is g more heritable than specific domain intelligence(s)?
  252. Yes, some subtests are more heritable than others: this is known as subtest heritability. And as it goes, the more g-loaded a subtest is, the more heritable that subtest is: meaning that g is more heritable than specific domain intelligence(s). See:
  253.  
  254. Rushton, J. P., & Jensen, A. R. (2005). Thirty years of research on race differences in cognitive ability. Psychology, Public Policy, and Law, 11, 235-294. (See Section 4: The g Factor and Mean Race–IQ Differences) http://philipperushton.net/wp-content/uploads/2015/02/Thirty-Years-of-Research-on-Race-Differences-in-Cognitive-Ability-2005-by-John-Philippe-Rushton-Arthur-Robert-Jensen.pdf
  255.  
  256. Rushton, J. P., & Jensen, A. R. (2010). The rise and fall of the Flynn Effect as a reason to expect a narrowing of the Black-White IQ gap. Intelligence, 38, 213-219. http://philipperushton.net/wp-content/uploads/2015/02/The-Rise-and-Fall-of-the-Flynn-Effect-as-a-Reason-to-Expect-a-Narrowing-of-the-Black%E2%80%93White-IQ-Gap-2010-by-John-Philippe-Rushton-Arthur-Robert-Jensen.pdf
  257.  
  258. Rushton, J. P. (2003). Race differences in g and the “Jensen Effect”. In H. Nyborg (Ed.),The scientific study of general intelligence: A tribute to Arthur R. Jensen (pp. 147-186). London: Elsevier. http://philipperushton.net/wp-content/uploads/2015/02/Race-Differences-in-g-and-the-Jensen-Effect-2003-by-John-Philippe-Rushton.pdf
  259.  
  260. Rushton, J. P. (1999). Secular gains in IQ not related to the g factor and inbreeding depression — unlike Black-White differences: A reply to Flynn. Personality and Individual Differences, 26, 381-389. http://philipperushton.net/wp-content/uploads/2015/02/iq-race-flynn-effect-rushton-personality-individual-differences-1999.pdf
  261.  
  262. The g Factor: The Science of Mental Ability by Arthur Jensen (see specifically chapter 7): http://emilkirkegaard.dk/en/wp-content/uploads/The-g-factor-the-science-of-mental-ability-Arthur-R.-Jensen.pdf
  263.  
  264. Genetic and environmental contributions to population group differences on the Raven’s Progressive Matrices estimated from twins reared together and apart by Rushton:
  265. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1914335/
  266.  
  267. We focused on the question of the extent to which there is a link between the g factor and heritability coefficients in the Japanese population. We carried out a meta-analysis of Japanese studies reporting heritabilities of all subtests of IQ batteries to examine whether they would give the same outcomes as Western studies. Correlations between heritabilities and g loadings were computed for all data points. The meta-analysis was based on four studies yielding six data points and showed a meta-analytical correlation of .38 (total N = 1808). We conclude that there is a clear link between the g factor and heritability coefficients in Japan, but that it contrasts with the quite strong correlations found in Western studies.
  268. Source: The correlation between g loadings and heritability in Japan: A meta-analysis by Jan te Nijenhuis https://www.researchgate.net/publication/265090206_The_correlation_between_g_loadings_and_heritability_in_Japan_A_meta-analysis
  269.  
  270. This paper addresses the question of how a genetic hierarchical model fits the Wechsler Adult Intelligence Scale (WAIS) subtests and the Raven Standard Progressive test score, collected in 194 18-year-old Dutch twin pairs.
  271. Source: Application of Hierarchical Genetic Models to Raven and WAIS Subtests: A Dutch Twin Study by Frühling V. Rijsdijk https://link.springer.com/article/10.1023%2FA%3A1016021128949?LI=true
  272.  
  273. We present the first report from the Swedish Adoption/Twin Study of Aging (SATSA) for cognitive data, including general cognitive ability and 13 tests of specific cognitive abilities. Consistent with the literature, heritabilities of specific cognitive abilities were lower than the heritability of general cognitive ability but nonetheless substantial. Average heritabilities for verbal, spatial, perceptual speed, and memory tests were, respectively, 58%, 46%, 58%, and 38%.
  274. Source: A Quantitative Genetic Analysis of Cognitive Abilities during the Second Half of the Life Span by N.L. Pedersen
  275. http://journals.sagepub.com/doi/abs/10.1111/j.1467-9280.1992.tb00045.x
  276.  
  277. In a re-analysis of the Raven Matrices data by Rushton, Bons, et al.
  278. (2007), we correlated the 36 item heritabilities on the Colored Matrices (e.g., from twins reared together) and the 58 on the Standard Matrices (e.g., from the Minnesota Study of Twins Reared Apart), with the item g loadings (e.g., frombthe item-total scores) and found a mean r of 0.47 (Pb0.01). Correcting the correlations raised the value from 0.55 to 1.00 (depending on whether using the test's alpha coefficient or the item's test–retest correlation). Arranging the items into parcels also raised the original value (The item-level data are available on-line at the journal; Rushton, Bons, et al., 2007).
  279. http://philipperushton.net/wp-content/uploads/2015/02/Genetic-and-Environmental-Contributions-to-Population-Group-Differences-on-the-Ravens-Progressive-Matrices-Estimated-from-Twins-Reared-Together-and-Apart-2007-by-John-Philippe-Rushton-Trudy-Ann-Bons-Philip-A.-Vernon-Jelena-%C4%8Cv.pdf
  280.  
  281. Hierarchical factor analyses involving Schmid-Leiman transformations (Schmid & Lei-man, 1957) were conducted on specific cognitive abilities data collected in a sample of 148 identical (MZ) and 135 same-sex fraternal (DZ) twin pairs. Two main questions were addressed: First, are genetic influences on specific cognitive abilities simply a reflection of their g loading, or are different sets of genes affecting separate abilities’? L Second, to the extent that specific cognitive abilities are affected by common genetic variance, how similar is the common genetic factor to a phenotypic factor reflecting R’? Model fitting.
  282. Results suggest that genetic influences on specific abilities are a reflection of both general intelligence and genetic influences specific to separate abilities and that loadings on the common genetic factor are more highly correlated with phenotypic loadings than are common environmental factor loadings.
  283. Source: Luo, D., Petrill, S. A., & Thompson, L. A. (1994). An exploration of genetic g: Hierarchical factor analysis of cognitive data from the Western Reserve Twin Project. Intelligence, 18(3), 335-347.
  284. http://psycnet.apa.org/record/1995-16934-001
  285.  
  286. What environmental effects affect g?
  287. Currently as of right now, we do not know of any ways to raise general intelligence permentally; however, we do have many studies showing what does not raise general intelligence. The studies below will be studies of things that do not raise g. Keep in mind, g and IQ are used in synonym a lot in research.
  288.  
  289. Are adoption gains in g? (Adoption does not raise g)
  290. Source: Are adoption gains on the g factor? A meta-analysis by Jante Nijenhuis http://www.sciencedirect.com/science/article/pii/S0191886914005248
  291.  
  292. Jensen's study; adoption gains not on g while biological SES is:
  293. Source: Adoption data and two g relates hypothesis by Arthur Jensen
  294. https://docs.google.com/file/d/0B0VDoaXaIou8TndHRHV4MTdRRUE/edit
  295.  
  296. Major interventions that attempt to give disadvantaged children better environments produce IQ gains while these interventions are ongoing, but these IQ advantages completely goes away by adulthood
  297. Source: The environment in raising early intelligence: A meta-analysis of the fadeout effect by JohnProtzko http://www.sciencedirect.com/science/article/pii/S016028961500135X
  298.  
  299. Are Headstart gains on the g factor? (No).
  300. Source: Are Headstart gains on the g factor? A meta-analysis by Jante Nijenhuisa http://www.sciencedirect.com/science/article/pii/S0160289614000932
  301.  
  302. Previous investigations into raising IQ show that after an intervention ends, the effects fade away. This paper is an attempt to understand one possible reason for this fadeout; the idea that the effects fade because they were not to the underlying construct g. The intervention indeed raised the g factor at age three. No effects were seen at follow-up assessments at ages five and eight after the intervention ended. Therefore, the raising IQ/raising g distinction is insufficient as an explanation for the fadeout effect, as changes to the environment can improve g and still fade.
  303. Source: Does the raising IQ-raising g distinction explain the fadeout effect? by John Protzko https://www.researchgate.net/publication/298807078_Does_the_raising_IQ-raising_g_distinction_explain_the_fadeout_effect
  304.  
  305. Training people how to take an IQ test does not raise g either.
  306. Source: Score gains on g-loaded tests: No g by Jante Nijenhuisa http://www.sciencedirect.com/science/article/pii/S0160289606000778
  307.  
  308. Previous research has indicated that education influences cognitive development, but it is unclear what, precisely, is being improved. Here, we tested whether education is associated with cognitive test score improvements via domain-general effects on general cognitive ability (g), or via domain-specific effects on particular cognitive skills. We conducted structural equation modeling on data from a large (n = 1,091), longitudinal sample, with a measure of intelligence at age 11 years and 10 tests covering a diverse range of cognitive abilities taken at age 70. Results indicated that the association of education with improved cognitive test scores is not mediated by g, but consists of direct effects on specific cognitive skills. These results suggest a decoupling of educational gains from increases in general intellectual capacity.
  309. Source: Is education associated with improvements in general cognitive ability, or in specific skills? by Ritchie, Stuart J. http://psycnet.apa.org/journals/dev/51/5/573/
  310.  
  311. There is a previously well-established relationship between socioeconomic status and cognitive ability. By having access to repeated measures of cognitive data across the second part of the life span, we were able not only to study the influence of childhood social class on mean-level cognitive performance, but also on change over time. Using reared-apart monozygotic and dizygotic twins and a control sample of twins reared together, we studied the effects of childhood socioeconomic environment on cognition in later life. We found an association between childhood social class and mean levels of cognitive performance, but not longitudinal trajectories of change. When controlling for genetic influences, there was no association of childhood social class and cognitive performance late in life.
  312. Source: Childhood social class and cognitive aging in the Swedish Adoption/Twin Study of Aging by Malin Ericsson https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5502597/
  313.  
  314. Does socioeconomic status affect the heritability of IQ?
  315. Some studies show that SES can affect how heritable IQ is through the process of gene-X-environment interaction. However, a recent meta analysis by Elliot M. Tucker-Drob and Timothy C. Bates showed that in industrial countries outside of the U.S., that SES does not have an effect on the heritability of IQ, while within the U.S. it has a small effect size of .076. Contra to Tucker-Drob and Bates though, a larger, more recent study in the state of Florida showed that there is no GxE affect on heritability due to SES: meaning that SES does not affect the heritability of IQ within the U.S. or that at least, the evidence is mixed and right now still up to speculation.
  316. Nevertheless, the question of if SES affects the heritability of IQ is not one of importance anyhow when talking about group differences as we can factor for any affects of SES GxE on heritability by factoring for SES between groups, side stepping altogether the problem of any possible SES affects on heritability.
  317.  
  318. Elliot M. Tucker-Drob and Timothy C. Bates' paper Large Cross-National Differences in Gene × Socioeconomic Status Interaction on Intelligence showing an effect size of .076: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4749462/
  319.  
  320. David N. Figlio's paper Socioeconomic status and genetic influences on cognitive development showing no GxE SES effect in America on the heritability of IQ: http://www.pnas.org/content/early/2017/11/07/1708491114
  321.  
  322. Ken B. Hanscombe's paper Socioeconomic Status (SES) and Children's Intelligence (IQ): In a UK-Representative Sample SES Moderates the Environmental, Not Genetic, Effect on IQ showing no GxE in the U.K.: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0030320
  323.  
  324. When does socioeconomic status (SES) moderate the heritability of IQ? No evidence for g × SES interaction for IQ in a representative sample of 1176 Australian adolescent twin pairs by Tim Bates: http://www.sciencedirect.com/science/article/pii/S0160289616300629
  325.  
  326. What happens when we do raise g?
  327. It goes away due to the fade out effect, which is that when people either a) stop training for it or b) get older the effect of the intervention fades away. The reason for it is people need to be trained constantly to be better than their natural selves, and because heritability increases with age. Meaning environment and environmental effects affect the variance within the general population less and less as time goes on. See Does the raising IQ-raising g distinction explain the fadeout effect? by John Protzko https://www.researchgate.net/publication/298807078_Does_the_raising_IQ-raising_g_distinction_explain_the_fadeout_effect
  328.  
  329. Can we measure g outside of IQ tests?
  330. Yes, as far as we are aware of, all cognitive tests to some extant or another have a g-factor to them. For example, the SAT, ACT, GCSE, NAEP, PISA and AFQT all measure g to some extant or another.
  331.  
  332. For example: SAT corralates to g:
  333. Source: Scholastic Assessment or g?
  334. The Relationship Between the Scholastic Assessment Test and General Cognitive Ability by Meredith C. Frey andDouglas K. Detterman Case
  335. https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.psychologicalscience.org/pdf/ps/Frey.pdf%3Forigin%3Dpublication_detail&ved=0ahUKEwjH76qW2_3VAhVW1mMKHa15BwEQFghVMAQ&usg=AFQjCNFwLAJrd0awYsSmotBh_fn0e7IKCA
  336.  
  337.  
  338. SAT and ACT correlate with g:
  339. Source: SAT and ACT predict college GPA after removing g by Thomas R. Coyle https://www.researchgate.net/publication/242788087_SAT_and_ACT_predict_college_GPA_after_removing_g
  340.  
  341. Is there anything we can use to proxy IQ?
  342. Yes, tests such the SAT, ACT, GCSE, NAEP, PISA and AFQT can all be used to proxy IQ tests as due to how well they all corralate to one another; we can also use real world outcomes such as income, education, and occupation to proxy IQ too due to how well they correlate as well.
  343.  
  344. Are there group differences in IQ?
  345. Yes, and here they are:
  346.  
  347. WAIS-IV Clinical Use and Interpretation by Weiss LG et al. (2010), Table 4.3, p. 118:
  348. White, 103.21 (13.77), 1540
  349. Black, 88.67 (13.68), 260
  350. Hispanic, 91.63 (14.29), 289
  351. Asian, 106.07 (15.01), 71
  352. Other*, 98.93 (13.99), 40
  353.  
  354. A review of 39 studies by the Clemson psychologist Philip Roth and colleagues reports that Hispanic-American IQs average 89.2 points.
  355. http://onlinelibrary.wiley.com/doi/10.1111/j.1744-6570.2001.tb00094.x/abstract
  356.  
  357. ETHNIC GROUP DIFFERENCES IN COGNITIVE ABILITY IN EMPLOYMENT AND EDUCATIONAL SETTINGS: A META-ANALYSIS by Phillip Roth
  358. http://onlinelibrary.wiley.com/doi/10.1111/j.1744-6570.2001.tb00094.x/abstract
  359.  
  360. Changes over time in the black–white difference on mental tests: Evidence from the children of the 1979 cohort of the National Longitudinal Survey of Youth by Charles Murray
  361. http://www.sciencedirect.com/science/article/pii/S016028960600078X
  362.  
  363. The magnitude and components of change in the black–white IQ difference from 1920 to 1991: A birth cohort analysis of the Woodcock–Johnson standardizations by Charles Murray
  364. http://www.sciencedirect.com/science/article/pii/S0160289607000190
  365.  
  366. No narrowing in mean Black–White IQ differences—Predicted by heritable g (Rushton, 2012)
  367. http://philipperushton.net/wp-content/uploads/2015/02/No-Narrowing-in-Mean-Black-White-IQ-Differences-Predicted-by-Heritable-g-2012-by-John-Philippe-Rushton.pdf
  368.  
  369. Rushton, J. P., & Jensen, A. R. (2006). The totality of available evidence shows race-IQ gap still remains. Psychological Science, 17, 921-922.
  370. http://philipperushton.net/wp-content/uploads/2015/02/The-Totality-of-Available-Evidence-Shows-the-Race-IQ-Gap-Still-Remains-2006-by-John-Philippe-Rushton-Arthur-Robert-Jensen.pdf
  371.  
  372. The rise and fall of the Flynn Effect as a reason to expect a narrowing of the Black–White IQ gap, by Rushton
  373. https://www.researchgate.net/publication/222646687_The_rise_and_fall_of_the_Flynn_Effect_as_a_reason_to_expect_a_narrowing_of_the_Black-White_IQ_gap
  374.  
  375. The Black-White IQ gap in the total sample of the Vietnam Experience, by Emil Kirkegaard (Note: this a DRAFT PAPER! and is not officially published.) https://osf.io/7whv6
  376.  
  377. An Update on the Secular Narrowing of the Black-White Gap in the Wordsum Vocabulary Test (1974-2012) by Meng Hu http://www.mankindquarterly.org/archive/issue/58-2/11
  378.  
  379. Adaptive behavior used to measure cognitive ability among groups in America by Harrison Kane. http://www.mankindquarterly.org/archive/issue/57-4/8
  380.  
  381. Rushton, J. P., & Jensen, A. R. (2005). Thirty years of research on race differences in cognitive ability. Psychology, Public Policy, and Law, 11, 235-294. (See Section 1: Race Differences in Cognitive Ability) http://philipperushton.net/wp-content/uploads/2015/02/Thirty-Years-of-Research-on-Race-Differences-in-Cognitive-Ability-2005-by-John-Philippe-Rushton-Arthur-Robert-Jensen.pdf
  382.  
  383.  
  384.  
  385. Are there race differences on different subtests?
  386. Yes, see:
  387.  
  388. Intellectual differences among Mexican Americans, Papagos and Whites, independent of g by Cecil R.Reynolds for subtest difference between whites and Mexicans. https://www.sciencedirect.com/science/article/pii/S0191886999000616
  389.  
  390. WISC-R subscale patterns of abilities of Blacks and Whites matched on Full Scale IQ by Cecil R.Reynolds for black-white IQ differences by subtest.
  391. https://www.researchgate.net/publication/232567661_WISC-R_subscale_patterns_of_abilities_of_Blacks_and_Whites_matched_on_Full_Scale_IQ
  392.  
  393. And see The Structure of Japanese Abilities: An Analysis in Terms of the Hierarchical Model of Intelligence by Richard Lynn for subtest differences between Asians and whites.
  394. https://link.springer.com/article/10.1007/BF02686586
  395.  
  396. Do mixed race individuals have intermediate IQs or intermediate IQ proxies?
  397. Yes, see: Admixture in the Americas: Regional and National Differences by John Fuerst https://www.researchgate.net/publication/298214364_Admixture_in_the_Americas_Regional_and_National_Differences
  398.  
  399. And The Minnesota Transracial Adoption Study by Scarr http://frihetspartiet.net/dokumenter/minnesota-transracial-adoption-study.pdf
  400.  
  401. Is the black-white IQ gap closing?
  402. The debate is over whether the gap narrowed just in the 70s and 80s and then stopped or continued to narrow into the 2000s also. Whether it's closing our not comes down to how you want to slice the data by either birth year cohort or year taking cohort. If you slice the data by birth year cohort, the IQ gap stopped closing in the 80s; if you slice the data by year taking cohort, the IQ gap is closing.
  403. So which one slicing of data is more intack with reality? Well, birth year cohort is as things correlated to IQ, which should have gone up with the IQ gap closing, have not closed since the 80s: SAT scores, NAEP scores, and the income gap have all stagnated well before the 2000s. So as it currently stands, if you take into account the birth year cohort and the stagnation of IQ proxies, the IQ gap closed in the 70s and 80s from an 18 point IQ gap, to a 15 point IQ gap and has stagnated ever since. See sources below for general information in the closing of the IQ gap.
  404.  
  405. Changes over time in the black–white difference on mental tests: Evidence from the children of the 1979 cohort of the National Longitudinal Survey of Youth by Charles Murray
  406. http://www.sciencedirect.com/science/article/pii/S016028960600078X
  407.  
  408. The magnitude and components of change in the black–white IQ difference from 1920 to 1991: A birth cohort analysis of the Woodcock–Johnson standardizations by Charles Murray
  409. http://www.sciencedirect.com/science/article/pii/S0160289607000190
  410.  
  411. No narrowing in mean Black–White IQ differences—Predicted by heritable g (Rushton, 2012)
  412. http://philipperushton.net/wp-content/uploads/2015/02/No-Narrowing-in-Mean-Black-White-IQ-Differences-Predicted-by-Heritable-g-2012-by-John-Philippe-Rushton.pdf
  413.  
  414. Rushton, J. P., & Jensen, A. R. (2006). The totality of available evidence shows race-IQ gap still remains. Psychological Science, 17, 921-922.
  415. http://philipperushton.net/wp-content/uploads/2015/02/The-Totality-of-Available-Evidence-Shows-the-Race-IQ-Gap-Still-Remains-2006-by-John-Philippe-Rushton-Arthur-Robert-Jensen.pdf
  416.  
  417. The rise and fall of the Flynn Effect as a reason to expect a narrowing of the Black–White IQ gap, by Rushton
  418. https://www.researchgate.net/publication/222646687_The_rise_and_fall_of_the_Flynn_Effect_as_a_reason_to_expect_a_narrowing_of_the_Black-White_IQ_gap
  419.  
  420. The Black-White IQ gap in the total sample of the Vietnam Experience, by Emil Kirkegaard (Note: this a DRAFT PAPER! and is not officially published.) https://osf.io/7whv6
  421.  
  422. An Update on the Secular Narrowing of the Black-White Gap in the Wordsum Vocabulary Test (1974-2012) by Meng Hu http://www.mankindquarterly.org/archive/issue/58-2/11
  423.  
  424. Adaptive behavior used to measure cognitive ability among groups in America by Harrison Kane. http://www.mankindquarterly.org/archive/issue/57-4/8
  425.  
  426. Rushton, J. P., & Jensen, A. R. (2005). Thirty years of research on race differences in cognitive ability. Psychology, Public Policy, and Law, 11, 235-294. (See Section 1: Race Differences in Cognitive Ability) http://philipperushton.net/wp-content/uploads/2015/02/Thirty-Years-of-Research-on-Race-Differences-in-Cognitive-Ability-2005-by-John-Philippe-Rushton-Arthur-Robert-Jensen.pdf
  427.  
  428. SAT gap has stagnated since 1986:
  429. https://nces.ed.gov/fastfacts/display.asp?id=171
  430.  
  431. Income gap stagnated:
  432. https://thesocietypages.org/socimages/files/2008/10/picture-11.png
  433.  
  434. What is the black-white IQ gap if you control for socioeconomic status (income, education, and occupation)?
  435. Controlling for SES only lowers the IQ gap by 3-4 IQ points, leaving an IQ gap of 12 to 11 points.
  436. Sources: The G-Factor, p. 358 and Thirty years of research on race differences in cognitive ability.
  437. http://emilkirkegaard.dk/en/wp-content/uploads/The-g-factor-the-science-of-mental-ability-Arthur-R.-Jensen.pdf
  438. http://emilkirkegaard.dk/en/wp-content/uploads/J.-Philippe-Rushton-Arthur-R.-Jensen-THIRTY-YEARS-OF-RESEARCH-ON-RACE-DIFFERENCES-IN-COGNITIVE-ABILITY.pdf
  439.  
  440. What is Spearman's Hypothesis?
  441. Spearman's hypothesis is the hypothesis coined by Charles Spearman and Arthur Jensen that the magnitudes of the black-white differences on tests of cognitive ability positively correlate with the tests' g-loading. As in, the hypothesis is is that group differences will be mainly in general intelligence instead of specific domain intelligence.
  442.  
  443. For further reading, see:
  444. Rushton, J. P., & Jensen, A. R. (2005). Thirty years of research on race differences in cognitive ability. Psychology, Public Policy, and Law, 11, 235-294. (See Section 4: The g Factor and Mean Race–IQ Differences) http://philipperushton.net/wp-content/uploads/2015/02/Thirty-Years-of-Research-on-Race-Differences-in-Cognitive-Ability-2005-by-John-Philippe-Rushton-Arthur-Robert-Jensen.pdf
  445.  
  446. Race Differences in g and the Jensen Effect by Philippe Rushton:
  447. https://www.researchgate.net/publication/285106143_Race_Differences_in_g_and_the_Jensen_Effect
  448.  
  449. Is there any support for Spearman's Hypothesis?
  450. Yes, lots of it:
  451.  
  452. Rushton, J. P., & Jensen, A. R. (2005). Thirty years of research on race differences in cognitive ability. Psychology, Public Policy, and Law, 11, 235-294. (See Section 4: The g Factor and Mean Race–IQ Differences) http://philipperushton.net/wp-content/uploads/2015/02/Thirty-Years-of-Research-on-Race-Differences-in-Cognitive-Ability-2005-by-John-Philippe-Rushton-Arthur-Robert-Jensen.pdf
  453.  
  454. Race Differences in g and the Jensen Effect by Philippe Rushton:
  455. https://www.researchgate.net/publication/285106143_Race_Differences_in_g_and_the_Jensen_Effect
  456.  
  457. Genetic and environmental contributions to population group differences on the Raven’s Progressive Matrices estimated from twins reared together and apart by Rushton:
  458. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1914335/
  459.  
  460. Spearman's hypothesis using Raven's Progressive Matrices showing group differences are on g
  461. Source: Genetic and environmental contributions to population group differences on the Raven's Progressive Matrices estimated from twins reared together and apart by J. Philippe Rushton https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1914335/
  462.  
  463. Spearman's hypothesis using reaction time corralated to g on the Raven's Progressive Matrices test
  464. Source: Spearman's hypothesis tested with chronometric information-processing tasks by Aurther Jensen https://www.researchgate.net/publication/223041017_Spearman's_hypothesis_tested_with_chronometric_information-processing_tasks
  465.  
  466. Spearman's hypothesis states that differences between groups on subtests of an IQ battery are a function of the g loadings of these subtests. We examined Spearman's hypothesis in alternative tests of intelligence. We compared various groups. We carried out a meta-analysis based on 20 data points and a total of 8,322 Whites and 2,507 minority group members. Spearman's hypothesis was strongly confirmed with a mean r of .62. We conclude that group differences are to the same degree a function of g when they are measured with traditional test batteries as when they are measured using alternative test batteries
  467. Source: .Testing Spearman's hypothesis with alternative intelligence tests: A meta-analysis by Jan Te NijenhuiS
  468. https://www.researchgate.net/publication/318093048_Testing_Spearman's_hypothesis_with_alternative_intelligence_tests_A_meta-analysis
  469.  
  470. In France, are secular IQ losses biologically caused? A comment on Dutton and Lynn (2015)
  471. http://www.sciencedirect.com/science/article/pii/S0160289615001221
  472.  
  473. In this paper, we tested Spearman's hypothesis, comparing a group of Sudanese children and adolescents (N = 7226) with other groups of children and adolescents from Denmark, Cyprus, Croatia, Bosnia, South Africa, Estonia, Ukraine, Ireland, Russia, and Chile (total N = 13,105). The analyses were carried out on 19 comparisons between the Sudanese children and the other children. Aggregating all data points from the present study showed that Spearman's hypothesis was strongly confirmed with a sample-size–weighted r with a value of .70; it is argued that applying corrections for statistical artifacts would make this value substantially larger. These outcomes suggest that biological variables, including brain-related variables, are more important than non-biological variables in explaining group differences.
  474. Source: SPEARMAN’S HYPOTHESIS TESTED COMPARING SAUDI ARABIAN CHILDREN AND ADOLESCENTS WITH VARIOUS OTHER GROUPS OF CHILDREN AND ADOLESCENTS ON THE ITEMS OF THE STANDARD PROGRESSIVE MATRICES by Jan Te NijenhuiS http://www.sciencedirect.com/science/article/pii/S0160289616300800
  475.  
  476. Blacks generally score significantly lower on intelligence tests than Whites. Spearman’s hypothesis predicts that there will be large Black/White differences on subtests of high cognitive complexity, and smaller Black/White differences on subtests of lower cognitive complexity. Spearman’s hypothesis tested on samples of Blacks and Whites has consistently been confirmed in many studies on children and adolescents, but there are many fewer studies on adults. We carried out a meta-analysis where we collected the existing tests of Spearman’s hypothesis on adults and collected additional datasets on Black and White adults that could be used to test Spearman’s hypothesis. Our meta-analytical search resulted in a total of 10 studies with a total of 15 datapoints, with participants numbering 251,085 Whites and 22,326 Blacks in total. For all these data points, the correlation between the loadings of a general factor that is manifested in individual differences on all mental tests, regardless of content (g) and standardized group differences was computed. The analysis of all 15 data points yields a mean vector correlation of 0.57. Spearman’s hypothesis is confirmed comparing Black and White adults. The differences between Black and White adults are strongly in line with those previously found for children and adults
  477. Source: Spearman’s Hypothesis Tested on Black Adults: A Meta-Analysis by Jan Te NijenhuiS
  478. http://www.mdpi.com/2079-3200/4/2/6/htm
  479.  
  480. Spearman's hypothesis (SH) is a phrase coined by Arthur Jensen, which posits that the size of Black–White mean differences across a group of diverse mental tests is a positive function of each test's loading onto the general intelligence (g) factor. We found support for the weak form (.60) of SH in both methods, which suggests that both g and non-g factors were involved in the observed mean score differences between Black and White adults.
  481. Source: Testing Spearman's hypotheses using a bi-factor model with WAIS-IV/WMS-IV standardization data by Craig L. Frisbya
  482. http://www.sciencedirect.com/science/article/pii/S0160289615000549
  483.  
  484. Black/White differences in mean IQ have been clearly shown to strongly correlate with gloadings, so large group differences on subtests of high cognitive complexity and small group differences on subtests of low cognitive complexity. IQ scores have been increasing over the last half century, a phenomenon known as the Flynn effect. Flynn effect gains are predominantly driven by environmental factors. Might these factors also be responsible for group differences in intelligence? The empirical studies on whether the pattern of Flynn effect gains is the same as the pattern of group differences yield conflicting findings. A psychometric meta-analysis on all studies with seven or more subtests reporting correlations between g loadings and standardized score gains was carried out, based on 5 papers, yielding 11 data points (total N = 16,663). It yielded a true correlation of − .38, and none of the variance between the studies could be attributed to moderators. It appears that the Flynn effect and group differences have different causes. Suggestions for future research are discussed.
  485. Source: Is the Flynn effect on g?: A meta-analysis by Jan Te NijenhuiS
  486. http://www.sciencedirect.com/science/article/pii/S0160289613000226
  487.  
  488. Spearman's hypothesis, Jews vs non-Jews
  489. Source: Spearman's hypothesis tested on European Jews vs non-Jewish Whites and vs Oriental Jews: Two meta-analyses by Jan Te NijenhuiS
  490. http://www.sciencedirect.com/science/article/pii/S0160289614000130
  491.  
  492. Why is Spearman's hypothesis and group differences in g important?
  493. In short, due to group differences being in g, g being the most heritable, and the environment having little impact on g, it means that group differences are heritable. If group differences were not on g - aka, the most environmentally impacted subtests - it would mean group differences are environmental in orgin. But they're not on g: instead group differences are on the most heritable subtests, showing a big red flag that group differences are heritable in orgin.
  494. It also too indicates that education, SES, and early life inventions are unlikely to close group IQ differences as environmental effects do not raise g (see "What environmental effects affect g?").
  495.  
  496. Is there any genetic data showing between group heritability for IQ or IQ proxies?
  497. Some, but it's sparse. That being said, I have not seen a single study showing there is no genetic data for between group heritability.
  498.  
  499. A review of intelligence GWAS hits: Their relationship to country IQ and the issue of spatial autocorrelation by Davide Piffer
  500. http://www.sciencedirect.com/science/article/pii/S0160289615001087
  501.  
  502. Factor Analysis of Population Allele Frequencies
  503. as a Simple, Novel Method of Detecting Signals of Recent Polygenic Selection: The Example of Educational Attainment and IQ by Davide Piffer http://www.mankindquarterly.org/archive/issue/54-2/3
  504.  
  505. Haplogroups as evolutionary markers of cognitive ability by HeinerRindermann http://www.sciencedirect.com/science/article/pii/S0160289612000529
  506.  
  507. What is regression to the mean and do groups regress to their means?
  508. Here is Murray's paper that answer both questions more elegantly than I can: Regression to the mean: Black-White Difference: Evidence from the NLSY by Charles Murray:
  509. http://www.lrainc.com/swtaboo/taboos/cmurraybga0799.pdf
  510.  
  511. Also see John Fuerst's paper on regression to the mean: https://humanvarieties.org/2017/07/01/measurement-error-regression-to-the-mean-and-group-differences/
  512.  
  513. Are IQ tests bias towards non-whites?
  514. No; see Arthur Jensen's book Bias in Mental Testing: http://emilkirkegaard.dk/en/wp-content/uploads/Bias-in-Mental-Testing-Arthur-R.-Jensen.pdf
  515.  
  516. See Survey of opinions on the primacy of g and social consequences of ability testing: A comparison of expert and non-expert views by Charlie L. Reeve which found that experts agree that IQ tests are not racially bias.
  517. https://www.sciencedirect.com/science/article/pii/S0160289608000305
  518.  
  519. Also see the American Psychological Association publication entitled “Intelligence: Knowns and Unknowns” which concluded “Considered as predictors of future performance, the tests do not seem to be biased against African Americans”: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.134.1282&rep=rep1&type=pdf
  520.  
  521. Does the Flynn effect matter for group differences?
  522. In short: no. The reason why is that the Flynn Effect is on subtests that are the least g-loaded while group differences are on subtests that are the most g-loaded. So they're unrelated when it comes to group differences in g. And funny enough, even James Flynn, which the Flynn Effect is named after, says that the Flynn Effect and group differences are not related: "The results appear to me correct: the magnitude of white/black IQ differences on Wechsler subtests at any given time is correlated with the g loadings of the subtests; the magnitude of IQ gains over time on subtests is not usually so correlated; the causes of the two phenomena are not the same. I have acknowledged this many times (Flynn, 2008, p. 79; 2012, p.136)."
  523.  
  524. See the following studies to see that the Flynn Effect and group differences are unrelated:
  525.  
  526. The rise and fall of the Flynn Effect as a reason to expect a narrowing of the Black–White IQ gap by Rushton
  527. https://www.researchgate.net/publication/222646687_The_rise_and_fall_of_the_Flynn_Effect_as_a_reason_to_expect_a_narrowing_of_the_Black-White_IQ_gap
  528.  
  529. Secular gains in IQ not related to the g factor and inbreeding depression — unlike Black-White differences: A reply to Flynn by Rushton
  530. https://www.researchgate.net/publication/251468974_Secular_gains_in_IQ_not_related_to_the_g_factor_and_inbreeding_depression_-_unlike_Black-White_diAerences_A_reply_to_Flynn
  531.  
  532. Rushton, J. P., & Jensen, A. R. (2005). Thirty years of research on race differences in cognitive ability. Psychology, Public Policy, and Law, 11, 235-294. (See Section 12: How Well Have Culture-Only Theories of Mean Race–IQ Differences Held Up?) http://philipperushton.net/wp-content/uploads/2015/02/Thirty-Years-of-Research-on-Race-Differences-in-Cognitive-Ability-2005-by-John-Philippe-Rushton-Arthur-Robert-Jensen.pdf
  533.  
  534. Score gains on g-loaded tests: No g by Jante Nijenhuisa
  535. http://www.sciencedirect.com/science/article/pii/S0160289606000778
  536.  
  537. The rule-dependence model explains the commonalities between the Flynn effect and IQ gains via retesting by Elijah L. Armstronga http://www.sciencedirect.com/science/article/pii/S1041608013001556
  538.  
  539. Is the Flynn effect on g?: A meta-analysis by Jante Nijenhuisa
  540. http://www.sciencedirect.com/science/article/pii/S0160289613000226
  541.  
  542. The secular rise in IQs: In Estonia, the Flynn effect is not a Jensen effect by Olev Must http://www.sciencedirect.com/science/article/pii/S0160289603000138
  543.  
  544. Controlling for increased guessing enhances the independence of the Flynn effect from g: The return of the Brand effect by Michael Anthony Woodley http://www.iapsych.com/iqmr/fe/LinkedDocuments/woodley2014.pdf
  545.  
  546. What are hollow gains?
  547. Hollow gains is a term coined by Arthur Jensen in his 1998 book The G-Factor: hollow gains are gains in IQ that are either a) not in g; or b) have no validity (they did increase performance outside of an IQ or IQ related test). To give you an example, us increasing IQ through school is hollow gains due to the increase in IQ not raising general intelligence.
  548. So in short, hollow gains are IQ gains that are hollow for g.
  549.  
  550. What is a Jensen Effect?
  551. A Jensen Effect is any effect that raised general intelligence; the term was coined by Phillip Rushton in the 1990s.
  552.  
  553. What is an anti-Jensen Effect?
  554. An anti-Jensen effect is an effect that raised IQ but did not raise general intelligence.
  555.  
  556. What is the Default Hypothesis?
  557. The Default Hypothesis, which was coined by Arthur Jensen in the 1990s, is the hypothesis that between group heritablity should be hypothesized at the same amount as within group heritability until evidence shows otherwise. For example, if within group heritability for IQ is .8, then the default hypothesis for between group heritability should too be .8 as the evidence for general heritability within the general population points towards .8.
  558.  
  559. Is brain size correlated to IQ?
  560. Yes, see:
  561.  
  562. Meta-Analysis of Associations Between Human Brain Volume And Intelligence Differences: How Strong Are They and What Do They Mean? by Jakob Pietschnig.
  563. https://archive.is/3fRPJ
  564.  
  565. Small to medium magnitude Jensen effects on brain volume: A meta-analytic test of the processing volume theory of general intelligence by Woodley.
  566. http://www.sciencedirect.com/science/article/pii/S1041608016302072
  567.  
  568. Brain volume and intelligence: The moderating role of intelligence measurement quality by Gilles E.Gignaca.
  569. https://www.sciencedirect.com/science/article/pii/S0160289616303385
  570.  
  571. Chapter 6. Factors Influencing the Relationship Between Brain Size and Intelligence by Gilles E Gignac https://www.researchgate.net/publication/239987172_Chapter_6_Factors_Influencing_the_Relationship_Between_Brain_Size_and_Intelligence
  572.  
  573. John Fuerst's paper on IQ and brain size: https://abc102.wordpress.com/2011/02/17/brain-size-and-correlates-with-iq/
  574.  
  575. Does brain morphology affect IQ?
  576. Yes, see:
  577.  
  578. Jakob Seidlitz' paper Morphometric Similarity Networks Detect Microscale Cortical Organization and Predict Inter-Individual Cognitive Variation http://www.cell.com/neuron/fulltext/S0896-6273(17)31092-9
  579.  
  580. Toga AW's paper Genetics of brain structure and intelligence. http://www.ncbi.nlm.nih.gov/pubmed/15651931
  581.  
  582.  
  583. Further and random readings (thanks to Pericles):
  584. Theory of Multiple Intelligences:
  585. https://youtu(dot)be/s2EdujrM0vA
  586.  
  587. Concise theory on g factor:
  588. https://youtu(dot)be/MmaQCPJOD2Y
  589.  
  590. Race differences in intelligence:
  591. https://youtu(dot)be/J4KNnRBUhGo
  592. https://youtu(dot)be/nTdMY9RI-7E
  593.  
  594. The Bell Curve summary:
  595. https://youtu(dot)be/wzTca9UjS-U
  596.  
  597. The Bell Curve audiobook:
  598. https://youtu(dot)be/3f6Ut7WzC4c
  599.  
  600. Theory on General Intelligence
  601. http://www.i3mindware(dot)com/5-iq-factors/general-intelligence
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