[R] Performing repeated T tests in R

[Rui Barradas]

Hello,

>
> #I wrote a blank matrix with 1 row and 10000 columns. 
>

Why not a vector? (It would be a column vector, which might not fit your
needs.)
And though not really a problem, the matrix is called 't', the name of R's
transpose function.
I can become confusing, maybe you could call it 'tstat' or something like
that.

>
> #But i need to do this for all 10000 pairs of samples:
> #I tried to write a loop
> 
> for(j in 1:10000) {t[,1:10000]<-t.test(sampc1[, j],sampc2[, j])$statistic}
> 
> #but this fills each column in the matrix with the same exact t value.  
> 

And that value is the test statistic of the last test.
This is because the index of the results matrix/row vector should be

for(j in 1:10000) {t[, j]<-t.test(sampc1[, j],sampc2[, j])$statistic}

Or, since it has only one row,  t[1, j]

Or, with the suggestions above,

tstat <- double(10000)
for(j in 1:10000) {tstat[j]<-t.test(sampc1[, j],sampc2[, j])$statistic}


Hope this helps

Rui Barradas


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