Distribution of p values computed from unequal variance t-test in patients with ER-negative and ER-positive tumors, respectively. A, Gene expressions were compared between ER-negative tumors that had pathologic complete response and those that had a lesser response to preoperative chemotherapy. The resulting p-values for all comparisons were modeled as beta uniform mixture. The straight line indicates the contribution of the uniform component, and the curved line is the fitted beta-distribution from the observed values. Deviation above the straight line indicate p-values that may represent true discovery. B, Distribution of p values in patients with ER-positive tumors.