Chapter 13 - 6851F_ch13_194_209 23/9/02 10:03 Page 194 13...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
13.1 (a) (i) 0.20 , P , 0.25. (ii) P 5 0.235. (b) (i) 0.02 , P , 0.025. (ii) P 5 0.0204. (c) (i) P . 0.25. (ii) P 5 0.3172. 13.2 H 0 : The marital-status distribution of 25- to 29-year-old U.S. males is the same as that of the population as a whole. H a : The marital-status distribution of 25- to 29-year-old U.S. males is dif- ferent from that of the population as a whole. Expected counts: 140.5, 281.5, 32, 46. X 2 5 161.77, df 5 3. P -value 5 7.6 3 10 2 35 < 0.0000. Reject H 0 . The two distributions are different. 13.3 H 0 : The genetic model is valid (the different colors occur in the stated ratio of 1:2:1). H a : The genetic model is not valid. Expected counts: 21 GG, 42 Gg, 21 gg. X 2 5 5.43, df 5 2. P -value 5 P ( X 2 2 . 5.43) 5 0.0662. There is no compelling reason to reject H 0 (though the P -value is a little on the low side). 13.4 H 0 : The ethnicity distribution of the Ph.D. degree in 1994 is the same as it was in 1981. H a : The ethnicity distribution of the Ph.D. degree in 1994 is different from the distribution in 1981. Expected counts 5 300 3 (1981 percents) 5 237, 12, 4, 8, 1, 38. X 2 5 61.98, df 5 5. P -value 5 P ( X 5 2 . 61.98) 5 4.734 3 10 2 12 < 0.0000. We reject H 0 and conclude that the ethnicity distri- bution of the Ph.D. degree has changed from 1981 to 1994. (b) The greatest change is that many more nonresident aliens than expected received the Ph.D. degree in 1994 over the 1981 figures. To a lesser extent, a smaller proportion of white, non-Hispanics received the Ph.D. degree in 1994. 13.5 Use a x 2 goodness of fit test. (b) Use a one-proportion z test. (c) You can construct the inter- val; however, your ability to generalize may be limited by the fact that your sample of bags is not an SRS. M&M’s may be packaged by weight rather than count. 13.6 H 0 : The age-group distribution in 1996 is the same as the 1980 distribution. H a : The age- group distribution in 1996 is different from the 1980 distribution. One simulation produced observed counts: 37, 35, 15, 13. The expected counts: 41.39, 27.68, 19.64, and 11.28 are stored in list L 4 , and the difference terms are assigned to L 5 . 1 O 2 E 2 2 / E 194 13 6851F_ch13_194_209 23/9/02 10:03 Page 194
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Inference for Tables 195 Note that none of the difference terms is very large. The test statistic is X 2 5 3.76, df 5 3, and the P -value 5 .2886. There is insufficient evidence to conclude that the distributions are different. The results of this simulation differ from those in the text; the reason may be due to different sample sizes or simply chance. 13.7 (a) H 0 : p 0 , p 1 5 p 2 5 . . . 5 p 9 5 0.1 vs. H a : At least one of the p ’s is not equal to 0.1. (b) Using randInt (0, 9, 200) L 4 , we obtained these counts for digits 0 to 9: 19, 17, 23, 22, 19, 20, 25, 12, 27, 16. (e) X 2 5 8.9, df 5 9, P -value 5 .447. There is no evidence that the sample data were generated from a distribution that is different from the uniform distribution. 13.8 Answers will vary. You should be surprised if you get a significant P -value. H 0 : The die is fair ( p 1 5 p 2 5 ... 5 p 6 5 1/6). H a : The die is not fair. Use the command randInt (1, 6, 300) L 1 to simulate rolling a fair die 300 times. In our simulation, we obtained the following frequency distribution: Side 1 2 3 4 5 6 Freq. 57 46 55 54 45 43 The expected counts under H 0 : (300)(1/6) 5 50 for each side. The test statistic is X 2 5 .98 1 .32 1 .5 1 .32 1 .5 1 .98 5 3.6, and the degrees of freedom are n 2 1 5 5. The P
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 16

Chapter 13 - 6851F_ch13_194_209 23/9/02 10:03 Page 194 13...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online