[R] Converting a categorical variable to multiple dichotemousvariables

[Jeremy Hetzel]

Shane,

Does this work?

# Your simulated data
subject=1:1000
treat=rbinom(1*1000,1,.13)
gender=rbinom(1*1000,1,.5)
eth=runif(1*1000, min=1, max=4)
cogat=rnorm(1*1000, 100, 16)
map=rnorm(1*1000, 200, 9)
growth=0
simtest=data.frame (subject=subject, treat=treat, gender=gender, 
eth=round(eth,digits=0), 
cogat=round(cogat,digits=0),map=round(map,digits=0),growth)
simtest<-transform(simtest, 
growth=rnorm(1000,m=ifelse(treat==0,0.1,0.5),s=0.03))
head(simtest)

# From Pablo above, but with unique() instead of levels(), since your eth is 
numeric, not a factor
simtest.dichotomous <- outer(simtest$eth, unique(simtest$eth), "==") + 0

# Combine
simtest.combined <- cbind(simtest, simtest.dichotomous)

head(simtest.combined)





Jeremy

Jeremy Hetzel
Boston University