We have conducted a repeated measures experiment in which we have registered the response time (RT) of each subject in 21 trials in each of 2 conditions. I have some questions related to the best analysis we can conduct... First, to reduce individual variability between subjects, we have standardize "within subjects", by substracting the mean of 42 trials of the subject to each trial, and the dividing the results by the SD of the subject.
Our objective is to compare both conditions, but collapsing data of both conditions and comparing means is not an option... We think that a better solution is to carry out a multilevel repeated measures analysis (in SPSS), but we have many questions:
Is the standardization of data a problem for the analysis? Because after standarsization the mean of 42 trials of each subject is 0, and SD=1...
I guess that Condition and Trial are Fixed factors, and subjects are the random factors... is it correct?
Since each trial is expected to be correlated with previous and following, and this correlation with other trials is expected to be weaker as they are further in time, I think that the covarianze type for repeated measures is Autorregressive... is it correct??
I hope someone could help me, I think I really need it... :S