Ivy,
My suggestion would be to model the group of trials without a reaction time as a separate condition
of no interest. When we have missing response time data in our study, often it is because subjects
are too slow to respond before the end of the trial -- but sometimes the subjects just simply
aren't paying attention (perhaps from dozing off). In any case, if you don't know what the
subjects are doing on a trial, it is really risky to make assumptions about their behavior in a model.
Doug Burman
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On Tue, 16 May 2006 12:38:28 pm CDT Ivy Estabrooke wrote:
Hello:
I am trying to use response times as a parametric modulator in analyzing my
event-related study. The study has two phases, first an implicit encoding
task which requires an overt resposne (living vs. non-living), and the
second is a recognition task (old vs. new) However, for some scans (about
15%) the subject did not respond and therefore I have no response time.
Has anyone encountered this problem? I am debating using the mean response
time for the missing values or the maximum response time for the subject?
Another thought is to use the mean maximum response time of the group?
Any thoughts?
Any help would be greatly appreciated!
Ivy
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