EBCR III - Cross-Sectional Study Design

Question 1

Cross-Sectional Studies

Answer 1

Purpose may just be descriptive w/o comparisons or evaluation of associations between an independent and dependent variable
-summary of characteristics of the study sample
-may or may not have a null hypothesis

Question 2

Cross-Sectional Studies

Answer 2

-can also examine associations between variable
-often conducted from survey data

Question 3

Cross-Sectional Studies

Answer 3

-Identification of exposure group and assessment of outcome occurs at the same point in time –cannot conclude which came first: exposure or outcome

Question 4

What are cross-sectional studies also referred to as?

Answer 4

prevalence studies
- It examines the prevalence of exposures, risk factors, disease

Question 5

What does prevalence include?

Answer 5

new and existing cases
(as opposed to incidence which is only new cases)

Question 6

Cross-Sectional Studies Steps-identify target pop.

Answer 6

• identify the target population
• select individuals that represent that target population (sampling –> random or convenience)

Question 7

Random (or probability) sampling

Answer 7

Sample more likely to represent the target population

Question 8

Convenience sampling

Answer 8

• sample is “easy” for investigators to obtain
• less likely to represent the target population

Question 9

Cross-Sectional Studies Steps- data collection

Answer 9

• can be prospective or retrospective
  –prospective data can be collected from interviews, mailings, internet
  –in-person or phone interviews may allow clarification of responses but require transportation to interview site or a phone
  –mailings and internet survey…

Question 10

Cross-Sectional Advantages

Answer 10

-inexpensive and fast
-no lost or follow-up
-can study more than one exposure and more than one outcome

Question 11

Cross-Sectional Limitations

Answer 11

-Can’t draw conclusion about the temporal relationship between exposure and outcome
-Prevalence only tell us how many have outcome at that point in time
-Response/participation bias
-Self-reporting
-Subject selection

Question 12

Self-reporting

Answer 12

-ex: race, diagnosis, medication, diet
-could it affect the relationship between exposure and outcome

Question 13

Subject selection

Answer 13

-is it generalizable to your pt/pt population
-is the selection process biased?
–was the way the subjects were chosen likely to influence the relationship between exposure and outcome

Question 14

response.participation bias