n <- 2500
prof <- rnorm(n, 1, 1)
ease <- rnorm(n, 1, 1)
slope <- prof + .25*ease + rnorm(n, 0.25, .15)
intercept <- ease + .25*prof + rnorm(n, 0, .10)
use1 <- intercept + rnorm(n, 0, .10)
use2 <- intercept + 1*slope + rnorm(n, 0, .05)
use3 <- intercept + 2*slope + rnorm(n, 0, .10)
use4 <- intercept + 3*slope + rnorm(n, 0, .05)

data21 <- data.frame(cbind(use1, use2, use3, use4, ease, prof))

names(data21)=c('use1', 'use2', 'use3', 'use4', 'ease', 'proficiency')

write.csv(data21, 'dataset21.csv', row.names=F)
