I have a data file with indicates pretest scores for a linguistics
experiment. The data are in long form so for each of 33 subjects there are
400 rows, one for each item on the test, and there is a column called
Correct that shows C for a correct response and E for an incorrect
response. I am trying to write a formula that will create a vector that
indicates the number of correct answers for each subject.
The following:
nrow(pretestdata[(pretestdata$Subject=="1" & pretestdata$Correct=="C"),])
gives the number of correct responses for subject 1, but I would like a
vector that indicates the number correct for each of 33 subjects.
Thank you sincerely for your assistance.
Kevin Burnham
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