Advanced Statistics Sat 2-5 Continuation of Exercise No. 3 1. For a sample of 20 observations, ⅀D = 80 and ⅀D2 = 400. Is the difference between means significant at the 0.5 level for a directional test? 2. Convert the following measurements to ranks: X 3 2 1 8 5 7 6 4 Y 5 4 2 7 6 8 3 1 Calculate the Spearman’s rank correlation coefficient. Does the coefficient obtained differ significantly from 0? 3. The following are the numbers of sales which a random sample of nine salesmen of industrial chemicals in California and a random sample of six salesmen of industrial chemicals in Oregon made over a fixed period of time: California: 41 47 62 39 56 64 37 61 52 Oregon: 34 63 45 55 24 43 4. The following are the heights of 32 persons when they began a weight-reducing diet and two weeks later: 212 and 195, 193 and 185, 241 and 225, 218 and 199, 205 and 194, 216 and 193, 215 and 205, 198 and 176, 200 and 188, 233 and 224, 258 and 240, 186 and 174, 289 and 263, 250 and 238, 225 and 213, 244 and 241, 260 and 249, 2099 and 185, 202 and 195, 219 and 214, 263 and 255, 241 and 228, 235 and 229, 200 and 188, 207 and 193. Use the 0.05 level of significance to test the null hypothesis that the mean weight loss of persons two weeks on this diet is 10.0 pounds against the alternative hypothesis that the weight loss is greater than that. 5. To compare freshmen’s knowledge of history, samples of 50 freshmen from each of two universities were given a special test. If those from the first university have an average score of 67.4 with a standard deviation of 5.0, while those from the second university have an average score of 62.8 with a standard deviation of 4.6, test at the 0.05 level of significance whether the difference between the two sample means is significant.
Posted on: Sat, 08 Mar 2014 06:45:36 +0000