CPHS Midterm, S01

Coverage: Study Design, How to Know What to Use, Sample Size Requirements Simplified, Data Entry and Validation, Basic Cohort Analysis, Basic Case-Control Analysis.

There are 3 parts of this exam: Part A (Closed-Book, worth 11 pts), Part B (Procedure Notebook, worth 17 pts), and Part C (Take Home, worth 6 pts). When you are done with Part A, turn it in and pick up Part B.

Part A (Closed Book)

An investigator wishes to study the relationship between low fruit and vegetable consumption and the risk of colon polyps. The independent variable in this analysis is _____________________________________ [fill in blank] and the dependent variable is ____________________________________________ [fill in].

The investigator will study an equal number of people who have low fruit and vegetable consumption and a group that has high fruit and vegetable consumption, and follow them forward to determine the incidence of colon polyps in each group. Therefore, this is a [circle best response: cross-sectional / cohort study / case-control / clinical trial] study.

The measurement scale of the independent variable is [circle best response: continuous / ordinal / categorical]. The measurement scale of the dependent variable is [circle best response: continuous / ordinal / categorical]. The parameter we wish to estimate is [circle best response:).

Suppose the investigator finds a relative risk or odds ratio (I'm not saying which, ) of 2.5. This suggests that the relative increase in risk associated with low fruit and vegetable consumption is __________%.

The 95% confidence interval for the relative risk or odds ratio is (1.5, 4.1). This confidence interval suggests that there is a [circle best response: positive / negative / no] association between low vegetable and fruit consumption and colon polyps, and that this association [circle correct response [is / is not] significant.

New series of questions:

In the beginning of his article, Dallal identified the four Basics of Study Design. The first is "there must be a fully formed, clearly stated research question." Name one of the other three.

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

Dallal spoke of the importance of randomized, double-blind, controlled trials. What does "controlled" mean?

____________________________________________________________________________________

____________________________________________________________________________________

CPHS Midterm, S01, Part B (Procedure Notebook)

1. Below is data from a cohort study. Assume that the study was done well, and that biases are minimal. Estimate the relative risk associated with the exposure, calculate a 95% CI for the RR, and interpret your results. Address the direction, significance, and magnitude of the association. (In addressing the magnitude of the association, use quantitative terms such as a "300% increase in risk" or "4x the risk with exposure".) Show all work, including intermediate calculations. (If you need more space, use the back of this page.) [10 pts]

D+ D-

E+ 19 77

E- 14 170

2. Test the above data for significance. Show all hypothesis testing steps, including statements of the null and alternative hypotheses, statement of the alpha level, calculation of test statistics, and the formal conclusion. Show all work. [7 pts]

CPHS Midterm, S01, Part C (Take Home)

This is the take-home part of the exam. The goal is to measure your competency in creating a data set at this point. It should take a short time (say, half an hour) to complete.

You are to construct a data entry screen ("view") and empty project file for the data specified by the codebook below. The name of your data entry screen should be "CPHSexam." The name of your project should be "Yourlastname.MDB." You should complete this project alone, without assistance. (The grade is yours, and no one else's.)

Here's the codebook:

VarName Type Description
---------- ------------ -------------------------------
ID Numeric (###) Patient's identification number
AGE Numeric (##) Age (years)
SEX Text [UpperCase] Sex: M, F, .
HIV Yes/no HIV positive: Y, N, .
KAPOSISARC Yes/no Kaposi Sarcoma status: Y, N, .
REPORTDATE Date [dd/mm/yy] Report date
OPPORTUNIS Yes/no Opportunistic infection: Y, N, .

The file will contain no data (i.e., it will be an empty data set).

Please Email me your MDB file as an attachment, or turn in a floppy with your MDB file no later than next Tuesday, 3/27.1 I'd prefer the Email attachment method of delivery (I'll send you a receipt, once received), as this will allow for more timely grading of the exam, however, you can also give your floppy containing the MDB file to Mamie Pa in MH407. Please have her date the floppy when you turn it in.

This part of the exam is worth 8 points, with allocation as follows:

[view name]

[project name]

[variable names: 2 pts if perfect, 1 pt if partially flawed, 0 pts if badly flawed]

[variable types: 2 pts if perfect, 1 pt if partially flawed, 0 pts if badly flawed]