Power of the RV by sample size, denominator F-statistic, and correlation between measures. Power was calculated as the probability of obtaining a statistically significant RV from simulations. Factors not varied in simulation were held constant as in Table 1. The RVs were held constant in simulations and are parenthesized next to the measures in the legend. Abbreviations: RV, relative validity; QDIS, quality-of-life disease impact scale; KDQOL, kidney disease quality-of-life; SF-12, Short Form 12; PF, physical functioning; RP, role physical; BP, bodily pain; GH, general health; VT, vitality; SF, social functioning; RE, role emotional; PCS, physical component summary.