A series of experiments was designed to test a hypothesis that massive silver iodide seeding can, under specified conditions, lead to increased precipitation. The data from these experiments were reported in the article €œA Bayesian Analysis of a Multiplicative Treatment Effect in Weather Modification€ [Technometrics (1975) 17: 161€“ 166]. The rain volume falling from the cloud after seeding with silver iodide is reported here.

a. Is there significant evidence that seeding has increased the mean rainfall?
b. Is there a significant difference in the levels of variability in the amount of rainfall between seeded and unseeded clouds?
c. In order for seeding to be economically viable, it must on the average produce at least 100 more acre-feet of rainfall over usual (unseeded) rainfall. Is there evidence in this data set that seeding is economically viable?

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Rainfall (acre-feet) Unseeded Clouds 129.6 92.4 198.6 32.7 314 175 703.4 40.6 2745.6 200.7 1697.8 489.1 274.7 334.1 430.0 274.7 118.3 302.8 7.7 255.0 119.0 1656,0 115.3 978,0 242.5 Raintall (acre-feet) Seeded Clouds 26.1 11.5 1202.6 147.8 26.3 321.2 36.6 21.7 87.0 68.5 4.9 95.0 81.2 4.9 372.4 47.3 41.1 0.0 28.6 29.0 17.3 830.1 163.0 24.4 345.5 244.3