Validity
Construct validity of WPAI domain scores with MSQ-RFR, MSQ-RFP, and monthly migraine-headache days was assessed using Spearman’s correlation analyses at baseline. The Spearman’s rank correlation coefficient measures the strength and direction of association between two variables using a non-parametric correlation statistic with values ranging from -1 to + 1. We defined seven levels of correlation between outcomes based on the absolute values of Rho: 0.70–1.00 (high), 0.60–0.70 (moderate high), 0.50–0.60 (moderate), 0.40–0.50 (moderate low), 0.30–0.40 (low), 0.20–0.30 (negligible), and 0–0.20 (negligible-low).