RESULTS OF A RANDOMIZED HAIL SUPPRESSION EXPERIMENT IN NORTHEAST COLORADO - 2. SURFACE DATA BASE AND PRIMARY STATISTICAL ANALYSIS.

An extensive statistical analysis is made of the precipitation data collected during the randomized seeding experiment conducted by the National Hail Research Experiment during 1972-74, aimed at testing the feasibility of diminishing hail by seeding with silver iodide. The major conclusion is that no effect of seeding is detected at the 10% significance level. Even though the ratios of hailfall or rainfall on seed days to those on control days are generally greater than 1, the confidence intervals attached to these ratios are so large, because of the large natural variance in each response variable and the small sample size, that the true underlying seeding effects could in every case have ranged from substantial decreases to large increases.