Hi Lorna,

Thanks for your interest. Here are a few points to consider:

1. The column of ones should be included to account for the global mean. The significant result you found when removing the column of ones is most likely the mean effect (unless you have explicitly demeaned your measure of connectivity).

2. A contrast of [0 0 1] with a t-test will test for a positive correlation between your measure of connectivity and your third predictor variable. A contrast of [0 0 -1] with a t-test will test for a negative correlation. Finally, a contrast of [0 0 1] with a F-test will test for any correlation, both positive and negative (Based on your email, it seems this is what you want). So you have three options: [0 0 1] with t-test, [0 0 -1] with t-test or [0 0 1] with F-test.

3. The "One Sample" test is not relevant for your statistical design.

4. If your two predictor variables are highly correlated, you may want to consider removing one of the variables. There are other options to deal with correlated predictors.

Andrew