Jon and Spencer,

First of all, thanks for your insightful comments on my questions. I am
quite impressed by the level of support one finds in the r-help mailing
list. In particular, as Spencer pointed out in another post, I did not
do my homework and you have been overly kind in discussing the issue. I
promised Spencer privately that I will read the Posting Guide before
getting farther in the thread, but I would like just to give a short
answer:

* Jonathan Baron <baron@(protected)]:

> You still aren't saying whether you are doing this for each subject for
> the entire data set summed over subjects. If the latter, are you
> worried about subject variance? Do you think it possible that some
> subjects might show better performance in condition 2? Would you be
> happy if you tested a single subject and got the result? If subject
> variance is an issue, then you need to test "across subjects." One way
> to do that is to compute some performance measure for each subject and
> each condition and then do a matched-pairs t test across subjects.

Yes, I intend to do the test across subjects and subject variance is
indeed an issue in my case.

Thanks for your further suggestions, I will look at them carefully.

--
Rafael

______________________________________________
R-help@(protected)
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html