Epi200B_Homework1_Due_9AM_22Jan2024
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Industrial Engineering
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Feb 20, 2024
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Epi200B Winter 2024
Name:
Homework 1 Due on 1/22 @ 9 am (Monday) Questions 1 and 2 address: Wilcox AJ et al. Folic acid supplements and risk of facial clefts: national population based case-control study. BMJ 2007 Mar 3;334(7591):464.
1. a) What is the objective of the study?
b) Which study design did the investigators use for this purpose? c) What is the source population and the control-sampling design? d) List the main reasons why they chose this study design.
2. The potential confounders adjusted for in the study analyses did not change the observed estimates very much. Pick two from the list of potential confounders and discuss briefly how and why you agree or disagree with the investigator’s choice. Supply a DAG for each to illustrate and support your choice.
1
Epi200B Winter 2024
Name:
Homework 1 Due on 1/22 @ 9 am (Monday) 3.
Below is a table from a published article giving results of diesel emissions-lung cancer analyses:
a) Describe in your own words the findings in the table. Be concise.
b) Calculate the crude ORs for Gasoline (substantial level) and Diesel (substantial level) comparing the cases to each of the control groups (4 calculations in all) and briefly discuss the degree/direction of bias that was adjusted for in the analysis.
2
Epi200B Winter 2024
Name:
Homework 1 Due on 1/22 @ 9 am (Monday) 4.
An investigator wishes to perform a study to evaluate the effect of recent coffee drinking on the occurrence
of premature ventricular contractions (PVC) while performing a crossword puzzle among adults aged 35-
65. Six hundred adults were categorized as either regular coffee drinkers or non-drinkers. Assume that race and sex are risk factors for PVC. The data is shown in table below.
Race
Sex
Coffee drinker
Non-coffee drinker
Total
with PVC
Total
subjects
with PVC
Total
subjects
White
Male
80
90
3
10
100
Female
5
10
2
40
50
Asian
Male
45
60
8
90
150
Female
30
240
3
60
300
Total
160
400
16
200
600
a. Estimate the crude risk ratio for PVC, comparing coffee drinkers with non-coffee drinkers.
b. Estimate the 4 race-sex specific risk ratios.
3
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Epi200B Winter 2024
Name:
Homework 1 Due on 1/22 @ 9 am (Monday) 5.
A case-control study was done to examine the possible effect of recent oral contraceptive (OC) use on the occurrence of breast cancer in white women, ages 40-49. A group of 200 newly diagnosed cases living in upstate New York were compared with a group of 400 noncancer subjects selected from the same area. Since maternal history of breast cancer is known to increase the risk of the disease and since it is thought to
be associated with OC use, this variable was treated as a confounder. The table below shows the number of cases and controls, by exposure status and maternal history of breast cancer. a. Estimate the crude odds ratio for breast cancer, comparing OC users with nonusers. b. Estimate the two stratum-specific odds ratios. 4