My categorical variable, risk, is divided into three groups: ADV, HHM, and POV.
I'm looking for the average of these three groups for four continuous variables: read.5, read.6, read.7, and read.8, which are reading scores from grades 5 to 8.
It's the,2:5 of my dataset and an old textbook example. I used the following code, which appears to be incorrect despite the fact that it is correct according to the textbook example:
ddply(.data = MPLS[,2:5],.variables =.(MPLS$risk), myrisk
na.rm = TRUE,.fun = mean)
Earlier today, I received an error message for a section of code that read:
mean(MPLS[,2:5], na.rm = TRUE) - mymeans
When I googled it, I discovered that the R software had changed, and I needed to find another to operate with.