[R] Fwd: Help scoring a matrix of item responses

[Gabor Grothendieck]

Assuming this test data:

iris2 <- round(iris[1:10, 1:4])

Try this:

t(t(iris2) == c(iris2[1,])) + 0

On 2/13/06, Rick DeShon <deshon at msu.edu> wrote:
> Hi All.
>
> I'm new to R and trying to learn the data manipulation routines.  At the
> moment, this is the one that has me stumped.
>
> Imagine n test takers provide responses to k multiple choice items.  The
> result is a (n+1) x k matrix of responses where the first row of the matrix
> is a correct answer key.
>
> How could you transform the raw item responses into 1s (correct response)
> and 0s (incorrect responses) by comparing each test takers response to the
> correct answer key?
>
> Any direction would be appreciated!
>
> Rick
>
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