Bryson_Biostat_HW4

#H0: Observed = Expected #H1: Observed =/= Expected O = c ( 0 , 15 , 0 , 76 , 479 , 182 , 8 , 23 , 0 ) E_p = c (. 281 ,. 196 ,. 105 ,. 097 ,. 099 ,. 067 ,. 058 ,. 051 ,. 046 ) chisq.test (O, p= E_p) ## ## Chi-squared test for given probabilities ## ## data: O ## X-squared = 2900.5, df = 8, p-value < 2.2e-16 ### p-value<2.2e-16 < alpha=0.01. We reject H0; the observed MRI frequency is significantly different from the expected. Question 2 Question 2a In investigating cold tolerance of adults of a species of tropical butterfly, 68 of the butterflies (32 female and 36 males) were subjected to a cold temperature. 20 of the female survived so are 14 males. Complete the contingency table. With α = 0.05 , test whether survival of females are different from males in the experimental cold temperature. ( H int : you need to complete following table and then you may have to write the values in matix form ) Female Male Total Alive Dead Total 68 #H0:female survived = males survived #H1: female survived =/= males survived A = matrix ( c ( 20 , 12 , 14 , 22 ), nrow= 2 ) A ## [,1] [,2] ## [1,] 20 14 ## [2,] 12 22 chisq.test (A) ## ## Pearson's Chi-squared test with Yates' continuity correction ## ## data: A ## X-squared = 2.8924, df = 1, p-value = 0.089 chisq.test (A) $ expected

Present Not Present Hospital B 60 15 Hospital C 57 18 Hospital D 56 19 At α = ¿ 0.05, is there enough evidence to reject the claim that the proportions of those who were in the delivery room at the time of birth are the same? #H0: p1=p2 #H1: p1=/=p2 D = matrix ( c ( 66 , 9 , 60 , 15 , 57 , 18 , 56 , 19 ), nrow= 4 , byrow= TRUE ) D ## [,1] [,2] ## [1,] 66 9 ## [2,] 60 15 ## [3,] 57 18 ## [4,] 56 19 chisq.test (D) ## ## Pearson's Chi-squared test ## ## data: D ## X-squared = 5.0003, df = 3, p-value = 0.1718 chisq.test (D) $ expected ## [,1] [,2] ## [1,] 59.75 15.25 ## [2,] 59.75 15.25 ## [3,] 59.75 15.25 ## [4,] 59.75 15.25 ### p-value=0.1718 > alpha=0.05. We do not reject H0; the proportion of fathers present during delivery are significantly different from the fathers not present