using tapply with multiple variables
Since you did provide a description of your data (e.g., at least 'str(ALLDATA)') so that we know its structure, I will take a guess: tapply(ALLDATA$Correct, list(ALLDATA$Subject, ALLDATA$Time), function(x)sum(x=="C"))
On Sat, Apr 30, 2011 at 3:28 PM, Kevin Burnham <kburnham at gmail.com> wrote:
HI All, I have a long data file generated from a minimal pair test that I gave to learners of Arabic before and after a phonetic training regime. ?For each of thirty some subjects there are 800 rows of data, from each of 400 items at pre and posttest. ?For each item the subject got correct, there is a 'C' in the column 'Correct'. ?The line: tapply(ALLDATA$Correct, ALLDATA$Subject, function(x)sum(x=="C")) gives me the sum of correct answers for each subject. However, I would like to have that sum separated by Time (pre or post). ?Is there a simple way to do that? What if I further wish to separate by Group (T or C)? Thanks, Kevin ? ? ? ?[[alternative HTML version deleted]]
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