2.5. Statistical Analysis
within-women
Sample size calculations estimated that a total enrolment of 228 women (76 per arm) were required to detect a 2.5% difference in percent density change between any two arms at 80% power and considering a 5.0% standard deviation [Standard descriptive statistics were used to describe differences across the study arms. Fisher’s Exact tests were used for categorical and ordinal variables. Due to small sample sizes and skewed distributions, Kruskal-Wallis tests were used to test for differences across study arms for continuous variables. Wilcoxon-rank-sum tests were used to test for within-women changes over time.Kruskal-Wallis tests were also used to compare mammographic density change across study arms. The primary analysis included all women who completed the study (All hypothesis testing was two-sided, and a 