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RESULTSPrecipitation AnalysisRatios oC mean seeded band precipitation to mean not-seeded band precipitationwere computed for 168 gages lying over the land area upwind as wellas downwind of the seeding source. The band precipitation data at each stationwer, also ranked and the single tail Wilcoxon (Mann-Whitney) U test applied todetermine if the seeded sample showed significantly higher ranking than the notseededsampl-. Figures 4, 5, 6 and 7 show the precipitation ratios for each ofthe four years (1967-68, 1968-69, 1969-70 and 1970-71) that the Santa Barbarafieid study has been conducted. Each year shows high seed/no seed ratios centered60 to 90 miles downwind from the seeding source.While the patterns of the individual years are interesting, the statisticaliganificance of any one year's data is not particulaily high. However, when allfour years are combined producing a sample of 107 cases, the pattern becomesquite clear and the significance level is very high. This four year ratio mapis shown in Figure 8. The direct seeding effect in the primary area shows up asa region extending from the seeding site about 30 miles downwind with precipitationincreases of 50% or more during the seeded bands. The large scale effectsof seýding are indicated by a very large area with ratios of from 1.50 to over4.00 extending from north of Bakersfield to the Los Angeles area.Of the 168 precipitation stations used in this analysis, 60 showed statisticallysignificant differences in the ranks of seeded band precipitation comparedto unseeded bands at the 10'% level of confidence. Twenty-eight of these stationswere significant at the 5'/ level and four at the 13o level. The statistical testused fur this calculation was the non-parametric Wilcoxon (Mann-Whitney) test.In order to test the likelihood of such a large number of stations achievingsignificance at those levels, a Binomial Test was applied. This test statisticis given by the following formula:X -PNwhere X = numbe'r of stations significant at given probability level (P)P = problability levelN = number of stations in sample-10-