NUMERICAL ANALYSIS OF STATISTICAL POWER IN RANDOMIZED PRECIPITATION ENHANCEMENT EXPERIMENT

The statistical power of precipitation enhancement experiment in Gutian region is computed numerically with naive method. The results of’calculation showed, that the cloud seeding effects of 20-30% can be detected with power of 80% in 2-3 years duration with cross-over randomized design (a=0.05),and the duration of 4-5 years is necessary to detect corresponding increase bf rain with targetcontrol randomized design. In the randomized regression experiment of area, the deviations of statistical power are less than 5% generally with various evaluation methods: double ratio analysis, multiple event test and twosample regression analysis. The statistical powers for cloud type stratification are different, which is larger in stratiform category than cumuliform category owing to the strong areal correlation.