Re: [R] How create vector that sums correct responses for multiple subjects?

From: Jorge Ivan Velez <jorgeivanvelez_at_gmail.com>
Date: Thu, 24 Mar 2011 16:22:17 -0400

Hi Kevin,

Try this (untested):

sapply(split(pretestdata, Subject), function(l) with(l$Correct == "C"))

HTH,
Jorge

On Thu, Mar 24, 2011 at 3:24 PM, Kevin Burnham <> wrote:

> 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
>
> [[alternative HTML version deleted]]
>
>
> ______________________________________________
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>
>

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