Study Designs

Question 1

What are the goals of epidemiological studies ? (2 goals)

Answer 1

1. Describe disease (descriptive studies)

2. Identify associations (analytical studies)

Question 2

What are some characteristics of a good study ? (4)

Answer 2

Scientifically sound
Valid
Precise (repeatable)
Efficient

Question 3

What are some types of descriptive studies ?

Answer 3

Case reports
Case series
Cross-sectional descriptive studies

Question 4

What are some types of analytical studies ?

Answer 4

Clinical trials
Ecological
Cross-sectional analytical studies
Case-control
Cohort (protective and retrospective)

Question 5

Groups are compared in which study?

A. Descriptive
B. Analytical

Answer 5

B. Analytical

Question 6

Case report

Answer 6

Description of a disease/condition in ONE animal. It doesn’t provide generalizable knowledge

Question 7

Case series:

Answer 7

Description of several animals a with the same condition/clinical signs. 1/2 dozen to a dozen animals (not systematically selected). You can start to look at patterns in a case series. However, findings are not generalizable to the population. Strictly descriptive.

Question 8

T or F

Case reports and case studies provide information to stimulate hypotheses and future analytical studies

Answer 8

True

Question 9

Cross sectional:

Answer 9

Lot more individuals studied.. Sample is intended to represent the population (usually at one point in time). No groups are compared. This is descriptive. Measure of disease occurrence is usually prevalence.
Disadvantage: not good for causality (can’t tell if the exposure happened before the outcome

Question 10

What is an association?

Answer 10

When the exposure and outcome are dependent upon one another.

Question 11

Analytical studies compare groups on the basis of either _____ or _______

Answer 11

exposure or outcome

Question 12

To evaluate a new vaccine for distemper you vaccinate all dogs (1200) that enter your shelter in a one year period. None of them get distemper. What does this tell us about the effectiveness of the new vaccine ?

a. It tells us that the vaccine is effective
b. It tells us that the vaccine is not effective
c. it doesn’t tell us anything about the effectiveness of the vaccine

Answer 12

c. it doesn’t tell us anything about the effectiveness of the vaccine

Question 13

Why do we need controls ?

Answer 13

They are essential for measuring the effect of exposures.
The importance of the control group -> should be the same as you study group without the treatment.

Controls are the reference group

Question 14

Exposure groups compare:

Answer 14

exposed cohorts to non-exposed cohorts

count the number of subjects with the outcome

Question 15

Outcome groups compare:

Answer 15

diseased cases to non-diseased controls

count the number of subjects with the exposure