library(tidyverse)
## two samples t-test
df1 <- ... # independent variables
df2 <-  ... # dependent paired variables (time course or different measures on the same person)
t.test(df1$LI~df2$HQ) # for long format datasets, group variable after the ~

df1[df1$HQ == 'RH', 1] # dataset of one variable
rh <- df1$LI[df1$HQ == 'RH'] # vector
lh <- df1$LI[df1$HQ == 'LH']
shapiro.test(lh) # are these distributions normal?
shapiro.test(rh)
t.test(lh, rh) # for normal distributions
wilcox.test(lh, rh) # forn not normal distributions