Study Designs

Question 1

What studies are allocated/assigned to receive a treatment or exposure in order to study the effect?

Answer 1

Experimental

Question 2

Reasons why subjects may be selected for inclusion in a study…

Answer 2

1) because they represent a population
2) their exposure status
3) their outcome status

Question 3

What is the goal of sampling?

Answer 3

To select a sample that represents the population or group (exposure or outcome) being studied

Question 4

What type of studies are the best for demonstrating causality?

Answer 4

Experimental

Question 5

How do we measure the amount of disease occurrence? (Aka risk)

Answer 5

Incidence

Question 6

How are experimental studies essentially free of bias and confounding?

Answer 6

1) random allocation

2) blind or double-blind

Question 7

What two broad types of observational study designs compare groups?

Answer 7

1. Groups of populations

2. Groups of individuals

Question 8

Observational study designs are a misnomer in the sense that …

Answer 8

Investigators may measure, take samples, ask questions… (breaching “observation”)

Question 9

What type of study compares groups of populations and does not make measurements on individuals?

Answer 9

Ecological

Question 10

What is a major disadvantage of ecological studies?

Answer 10

Ecological fallacy*

-relationships observed at population levels may not hold true at the individual level

Question 11

What are “epidemiology” synonyms for Experimental studies?

Answer 11

“Randomized controlled trials”

“Clinical trials”

Question 12

What type of study might be used to best evaluate treatments/exposures involving nutrition, vaccine, antibiotics, etc?

Answer 12

Experimental

Question 13

How are groups compared in analytical studies?

Answer 13

1) comparison on the basis of exposure

2) comparison on the basis of outcome

Question 14

Cohort studies are selected on the basis of…?

Answer 14

Exposure

Question 15

What studies are individuals selected to represent a population?

Answer 15

Analytical cross-sectional

Question 16

Measure of disease occurrence in analytical cross-sectional studies?

Answer 16

Prevalence

Question 17

What type of study are individuals selected to represent outcome groups?

Answer 17

Case-control

Question 18

What is a way to control factors for confounding without allocating?

Answer 18

Matching! (I.e. Case-control studies)

Question 19

What is a staple advantage of case-control studies?

Answer 19

They’re good for studying RARE diseases where it’s difficult to get enough cases for stat analysis

Question 20

Retrospective vs. Prospective cohort studies…

Retrospective and prospective cohort studies select individuals based on their exposure, but how is retrospective cohort different?

Answer 20

The outcome is already established; the measure of association is PREVALENCE Ratio*

(In prospective cohort, the measure of association is relative risk)

Question 21

What 2 types of study designs use INCIDENCE as the measure of dz exposure?

Answer 21

Prospective cohort;

Clinical trial

Question 22

What type of study uses ODDS as a measure of dz exposure?

Answer 22

Case control!

Question 23

What type of study uses PREVALENCE/ODDS as a measure of dz exposure?

Answer 23

Cross-sectional

Question 24

What type of study uses PREVALENCE as the measure of dz exposure?

Answer 24

Retrospective cohort

Question 25

Which studies use RR/PR as a measure of association?

Answer 25

Prospective/retrospective cohort;

Clinical trials

Question 26

What study uses strictly OR as a measure of association?

Answer 26

Case control

Question 27

What study uses PR/OR as a measure of association?

Answer 27

Cross sectional

Question 28

What statistical test do we use for finding the difference in proportions in categorical data?

Answer 28

Chi-square test

Question 29

What type of statistical test do we use for continuous data to find the difference in means?

Answer 29

Student’s T-Test

Question 30

If there is an error in the measurements taken, what type of bias are we thinking?

Answer 30

Information bias!

Question 31

If there is an error in subject selection (sample is different than population), what type of bias are we thinking?

Answer 31

Selection bias!