# Get the number of measurements for each Study
SELECT count(Study),Study
  FROM [isb-cgc:tcga_201607_beta.DNA_Methylation_betas]
  GROUP BY Study

# Summarize mean and sd of beta values by study
SELECT Study,
       AVG(Beta_Value) as beta,
       STDDEV(Beta_Value) as stddev
  FROM [isb-cgc:tcga_201607_beta.DNA_Methylation_betas]
  GROUP BY Study order by stddev;