.-:*s 



APPENDIX 



theoretical 1:1 or 2:1 ratio is also ac- 

 cepted, the tesl i> rendered rather weak and 

 is not likely to be useful in describing the 

 nature of the genetic events involved. 



One way to increase the meaningfulness 

 of the tesl is to increase X. Another way 

 i- to change the level of confidence. At 

 the 1<»' , level of significance the "power" 

 of the test is greater than at the 5% level; 

 but there is a proportional increase in the 

 chance of rejecting the correct hypothesis. 

 Unless there is some special circumstance, 

 geneticists usually work at the 5% level and 

 increase the power of the test by increasing 

 X. Recall, however, that the size of s or a 

 decreases as the square root of N increases, 

 so that a fourfold increase in X only reduces 

 the standard deviation by a factor of 2. 



PROBLEMS 



A.35. Given j x = 8, X = 265, X = 12; test 

 at the 5% level of significance the 

 hypothesis that m = 11. 



A.36. Given a x 2 = 412, N = 53, X = 142; 

 test at the 5% level of significance 

 the hypothesis that m = 135. 



A. 37. What are the 95% confidence limits 

 for fi when a x = 4, X = 100, and 

 X = 35? 



A. 38. Given the following statistics: 1, 3, 

 4, 5, 5, 5, 5, 5, 6, 8; calculate X, 

 s x , and s x . 



A. 39. A new antibiotic was tested on pneu- 

 monia patients with the following 

 results: of those treated, 64 lived and 

 26 died (28.9% died); of those un- 

 treated, 36 lived and 24 died (40% 

 died). Test the hypothesis that the 

 treatment is not effective. 



A. 40. A random sample of six observations 

 drawn from a certain normal popu- 

 lation is as follows: 0, 2, 6, 6, 8, 14. 

 Test the hypothesis that m. the 

 population mean, equals 10. Use 

 the 5% level of significance. 



A. 1 1 . Normal barley seeds are treated with 

 X-rays and planted. ( )f 400 seed- 

 lings examined, 55 show sectors with 

 visible mutation. Test the hypothe- 

 sis that the true mutation frequency 

 at this dosage is 10%. 



A. 42. Denote the length of an ear of corn 

 by x inches. Explain exact ly what 

 is meant when someone says "the 

 probability of x being less than 7 

 is 0.05." 



A. 43. A random sample of 25 mice is taken 

 from a certain mutant strain. It is 

 hypothesized that the length of these 

 mice is approximately normally dis- 

 tributed. You find X equals 60 mm. 

 and s x is 10mm. (a) Test the hy- 

 pothesis that /u equals 61 mm. at the 

 5% level of significance, (b) Ex- 

 plain what is meant by "5% level of 

 significance" in this experiment. 



A. 44. Using the data of problem A. 43, find 

 confidence limits for m = 61 mm. 

 with 95% confidence. Explain the 

 practical meaning of your result. 



A. 45. Given the following data: 



Determine whether these two sam- 

 ples are statistically different. 

 A. 46. Under what circumstances can one 

 use the t table for values of r? 



