POPH192 Lecture 17 - Cross-Sectional and Ecological Studies

Question 1

when do you round when doing a prevalence calculation?

Answer 1

do not round if there is more than one step involved until your final answer

Question 2

what are the limitations of cross-sectional studies?

Answer 2

1) temporal sequencing
2) measure only prevalence not incidence
3) not good for studying rare outcomes or exposures
4) not good for accessing variable and transient (last for only a short amount of time) exposures or outcomes

Question 3

what is the equation for prevalence?

Answer 3

number of people with disease at a given point in time/ total number of people in the population at that point in time

Question 4

what are the advantages of cross-sectional studies?

Answer 4

• can assess multiple exposures or outcomes
• can be less expensive than some other study designs
• relatively quick

Question 5

what are ecological studies?

Answer 5

studies the compare exposures and outcomes across GROUPS not individuals

Question 6

what are ecological studies used for?

Answer 6

• to compare between populations
• to assess population level factors
• to consider hypotheses

Question 7

what are the limitations of ecological studies?

Answer 7

1) ecological fallacy (derives from ascribing to individuals the characteristics of the group)
2) cannot control for confounding
3) cannot she causation