Fig. 4.

Percentage change in the statistics from OLS to WLS: (WLS-OLS)/OLS * 100. Results are shown separately for the upper 20 percent of the most significantly activated voxels. The x-axis shows the mean t-value (averaged over OLS and WLS) for that percentile. (A) Change in the variance of $\widehat{\beta }$, estimated from the 16 occurrences of that condition across the experiment. (B) Change in the mean of $\widehat{\beta }$. (C) Change in the t-value of a mixed-effects model. (D) Change in the t-value of a fixed-effect model