Biostatistics Homework 3

These data are taken from the Carnegie Mellon Data and Story Libary: http://lib.stat.cmu.edu/DASL/ The orginal data came from: Chambers, Cleveland, Kleiner, and Tukey. (1983). Graphical Methods for Data Analysis. Wadsworth International Group, Belmont, CA, 351. Original Source: Simpson, Alsen, and Eden. (1975). A Bayesian analysis of a multiplicative treatment effect in weather modification. Technometrics 17, 161-166.

Out of 52 clouds, 26 were chosen at random to be seeded with silver nitrate in order to increase rainfall production. The data are as follows in units of acre-feet (volume). 

Unseeded_Clouds	Seeded_Clouds
1202.6	2745.6
830.1	1697.8
372.4	1656.0
345.5	978.0
321.2	703.4
244.3	489.1
163.0	430.0
147.8	334.1
95.0	302.8
87.0	274.7
81.2	274.7
68.5	255.0
47.3	242.5
41.1	200.7
36.6	198.6
29.0	129.6
28.6	119.0
26.3	118.3
26.1	115.3
24.4	92.4
21.7	40.6
17.3	32.7
11.5	31.4
4.9	17.5
4.9	7.7
1.0	4.1
  1. Test whether seeding increased rainfall by log transforming the data. Give the corresponding one-sided 95% confidence interval for the percentage increase in median rainfall production in the seeded clouds as compared to the unseeded ones.
  2. Test whether seeding increased rainfall by using non-parametric rank tests. Give the corresponding one-sided 95% confidence interval for the difference in median rainfall production between the seeded clouds and the unseeded ones.