12 May Public Health Epidemiology STATS HW (Confounding And Effect Modification)
Assignment: Problem Set: Confounding and Effect Modification
Public Health Epidemiology: Decoding the Science
DUE 1/25/18 9 P.M EST BE ON TIME..
This Assignment will allow you to practice individually and increase your skills assessing confounding and effect modification. Your goal for this Assignment is to compute and interpret the effects of confounding and effect modification.
Instead, copy and paste the problem set into a Word (or equivalent) document and complete all problems, showing your work. . Be sure that your completed problem set includes your responses to all questions and shows the calculations and/or reasoning to justify all answers.
1) A study followed 900,000 US adults from 1992 to 2008. At baseline, all participants were screened and determined to be cancer free and their body mass index (BMI) was calculated. Body mass index is a measure of obesity that is calculated using a person’s height and weight. Subjects were separated into the following groups according to their BMI: (a) normal weight, (b) slightly overweight, (c) moderately overweight and (d) greatly overweight. 57,145 deaths from cancer occurred in the population during the follow-up period. . The following results were seen for men and women when the heaviest members of the cohort (greatly overweight) were compared to those with normal weight:
Men: Risk ratio of cancer death = 1.5, 95% confidence interval = 1.1–2.1
Women: Risk ratio of cancer death = 1.6, 95% confidence interval = 1.4–1.9
- State in words your interpretation of the risk ratio given for the men.
- State in words your interpretation of the risk ratio given for the women.
- Are these results confounded by gender?
- The authors stated that they controlled for confounding many risk factors using a multivariate analysis. State an alternative method that the authors could have used to control for confounding in the design or analysis. In addition, name two confounding variables that you think should be controlled using this method.
2) A cohort study was undertaken to examine the association between high lipid level and coronary heart disease (CHD). Participants were classified as having either a high lipid level (exposed) or a low or normal lipid level (unexposed). Because age is associated with both lipid level and risk of heart disease, age was considered a potential confounder or effect modifier and the age of each subject was recorded. The following data describes the study participants: Overall, there were 11,000 young participants and 9,000 old participants. Of the 4,000 young participants with high lipid levels, 20 of them developed CHD. Of the 6,000 old participants with high lipid levels, 200 of them developed CHD. In the unexposed, 18 young and 65 old participants developed CHD.
- Construct the appropriate two by two tables using the data given above. Be sure to label the cells and margins.
- Calculate the appropriate crude ratio measure of association combining the data for young and old individuals.
- Now, perform a stratified analysis and calculate the appropriate stratum-specific ratio measures of association. What are they?
- Do the data provide evidence of effect measure modification on the ratio scale? Justify your answer.
3) A study used self-administered mail questionnaires to gather data on height and weight in order to calculate a measure of obesity. Which of the following types of problems were likely avoided by this method of data collection, and why?
- Interviewer bias
- Exposure misclassification
- Confounding
- Selection bias
- Loss-to-follow-up
Our website has a team of professional writers who can help you write any of your homework. They will write your papers from scratch. We also have a team of editors just to make sure all papers are of HIGH QUALITY & PLAGIARISM FREE. To make an Order you only need to click Ask A Question and we will direct you to our Order Page at WriteDemy. Then fill Our Order Form with all your assignment instructions. Select your deadline and pay for your paper. You will get it few hours before your set deadline.
Fill in all the assignment paper details that are required in the order form with the standard information being the page count, deadline, academic level and type of paper. It is advisable to have this information at hand so that you can quickly fill in the necessary information needed in the form for the essay writer to be immediately assigned to your writing project. Make payment for the custom essay order to enable us to assign a suitable writer to your order. Payments are made through Paypal on a secured billing page. Finally, sit back and relax.
About Writedemy
We are a professional paper writing website. If you have searched a question and bumped into our website just know you are in the right place to get help in your coursework. We offer HIGH QUALITY & PLAGIARISM FREE Papers.
How It Works
To make an Order you only need to click on “Order Now” and we will direct you to our Order Page. Fill Our Order Form with all your assignment instructions. Select your deadline and pay for your paper. You will get it few hours before your set deadline.
Are there Discounts?
All new clients are eligible for 20% off in their first Order. Our payment method is safe and secure.