Research has shown that there are few known behavioral risk factors for breast cancer among women in the US, despite the numerous studies investigating the outcome. One such risk factor that has been suggested, parity, or number of pregnancies experienced by a mother over the course of her lifetime, has been determined to have a protective effect against the disease. In order to test this finding, researchers attain medical records from a major cancer institute and recruit a group of women with breast cancer frequency matched to a group of cancer-free controls attending the hospital with another non-fatal illness. The exposure history of number of pregnancies is recorded for each patient. The following table represents a preliminary analysis of the results. Breast Cancer No Breast Cancer Total No Children 129 36 165 1-3 Children 63 290 353 >3 Children 27 112 139 Total 219 438 657 A) What type of study is being conducted here? B) Conduct a formal hypothesis test to determine if there is a relationship between the various levels of exposure and the outcome. Write out your null and alternative hypotheses, Chi-squared stat value, the degrees of freedom, Pvalue and interpret your results at an alpha level of 0.05. C) Calculate the appropriate risk measurement (OR) between each category of exposure relative to the category of “No Children” as the reference non-exposed group. D) Using results from part B and C, discuss the relationship between parity and risk of breast cancer in this study
Research has shown that there are few known behavioral risk factors for breast cancer among women in the US, despite the numerous studies investigating the outcome. One such risk factor that has been suggested, parity, or number of pregnancies experienced by a mother over the course of her lifetime, has been determined to have a protective effect against the disease. In order to test this finding, researchers attain medical records from a major cancer institute and recruit a group of women with breast cancer frequency matched to a group of cancer-free controls attending the hospital with another non-fatal illness. The exposure history of number of pregnancies is recorded for each patient. The following table represents a preliminary analysis of the results.
|
|
Breast Cancer |
No Breast Cancer |
Total |
|
No Children |
129 |
36 |
165 |
|
1-3 Children |
63 |
290 |
353 |
|
>3 Children |
27 |
112 |
139 |
|
Total |
219 |
438 |
657 |
A) What type of study is being conducted here?
B) Conduct a formal hypothesis test to determine if there is a relationship between the various levels of exposure and the outcome. Write out your null and alternative hypotheses, Chi-squared stat value, the degrees of freedom, Pvalue and interpret your results at an alpha level of 0.05.
C) Calculate the appropriate risk measurement (OR) between each category of exposure relative to the category of “No Children” as the reference non-exposed group.
D) Using results from part B and C, discuss the relationship between parity and risk of breast cancer in this study.
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