Essay Design of Case-Control Study & Breast Cancer or Participation In Mammography Screening – Nursing Assignment Help

Assignment Task

Question 
You are a part of a research team and you have been asked to give advice on the design of a case-control study to investigate the association between breast cancer and participation inmammography screening. The research team wants to be able to detect an odds ratio of at least 0.5 using a two-sided significance test at the 5% level. It is estimated that 50% of the contropopulation will have participated in mammography.

(a) If an equal number of cases and controls could be recruited in this study, what is the required sample size to achieve a study power of (i) 80% and (ii) 90%

(b) One of the researchers thinks that the prevalence of the exposure (mammography screening) in the population would be 30%, not 50%.

i. If the researchers would like to achieve 90% power, how many cases and controls would be required to detect the same odds ratio as in (a)?

ii. If the prevalence of exposure in the population was not known, would it be better to assume the prevalence of exposure in the population was 30% or 50%? Why? 

(c) The study team inform you that they may not be able to recruit as many cases asyou have estimated in (a). What should they do to keep the same power, detectableeffect size, and level of significance as in (a)? What is the disadvantage of this approach?