Hello All. First-time poster, long-time reader.
I am examining how differences in activation correlate with baseline performance of a videogame (Space Fortress). I have been using the Single-Group Average with Additional Covariate design, but there may be a problem. The videogame is designed such that scores can be either positive or negative; scores range from -4000 to +4000, with most falling between the -1000 to +1000 range.
The mean of this behavioral measure is -196, which means that de-meaning this variable consists of adding 200 points to each subject's score. This means that de-meaning is having next to no effect (I have done the same analysis without de-meaning and the difference is barely noticeable).
My question is this: Does the fact that my covariate ranges from positive to negative, and that de-meaning has such a small effect, make the Single-Group Average with Additional Covariate design unsuitable for my data? Any advice would be much appreciated. Thank you,
~Aldis Sipolins
|