Question

4. (15 pts) Hip dysplasia is a hip socket abnormality that affects many large breed dogs. A review of medical records of dogs seen at 27 veterinary medical teaching hospitals found that hip dysplasia was more common in Golden retrievers than in Border Collies; the data are shown in the following table. Border collie Golden retriever Hip dysplasia Yes 3,995 42,946 46,941 221 No 5,007 5,228 Total (a) Calculate the relative risk of hip dysplasia for Golden retriever compared to border collie. (b) Calculate the sample value of odds ratio. (c) Construct a 95 % confidence interval for the population value of the odds ratio. (d) Interpret the confidence interval from the part (b) in the context of this setting.

thats all I have

Answer 1

Odds ratio calculator Cases with positive (bad) outcome Number in exposed group: 3995 a Number in control group: 42946 C Cases with negative (good) outcome Number in exposed group: 221 b Number in control group: 5228 d Test Results Odds ratio 95 % CI: z statistic Significance level 2.2006 1.9161 to 2.5274 11.166 P<0.0001 Computational notes The odds ratio (OR), its standard error and 95% confidence interval are calculated according to Altman, 1991. The odds ratio is given by a/b OR=- c/d axd bxc with the standard error of the log odds ratio being 1 SE{In(OR) = /1 - Va + 1 - b + 1 - c +- d and 95% confidence interval 95% CI = exp ( In(OR) – 1.96 x SE{In(OR)}) to exp ( In(OR) +1.96 x SE{In(OR)})

A)

The relative risk or risk ratio is given by RR = a/(a+b) c/(c+d)

Relative risk	2.0984

B)

Odds ratio	2.2006

C)

95 % CI:	1.9161 to 2.5274