Lecture 3 - case series, time series, ecol study designs

Question 1

common use

Answer 1

generate hypotheses

time series and ecol rarely to test

Question 2

def. case series

Answer 2

describes individual cases

- can look for commonalities in lit

Question 3

when to use case series

Answer 3

new disease or against conventional wisdom

Question 4

strengths and weaknesses of case series

Answer 4

strengths 
- cheap and easy
- raise questions about convention
weak
- no comparison group
- no hypos
- don't offer explanation

Question 5

def. time series

Answer 5

compare rates of events over time

• compare series of measures before and after
• look for change in means and medians

Question 6

use of time series

Answer 6

• study impact of policy and new interventions

Question 7

when to use time series

Answer 7

• easy access to existing data

- asses policy change

Question 8

strength of time series

Answer 8

• cheap and easy

- done when can’t get a good control group

Question 9

weak of time series

Answer 9

• need stable rates before intervention implemented

- doesn’t control for concurrent events

Question 10

def. ecological study

Answer 10

• aggregate info on indivs. that compres rates of exposures and outcomes across regions

Question 11

problem with ecol

Answer 11

ecological fallacy - inferences from population that are applied to individuals

Question 12

common uses of ecol

Answer 12

explore association where aggregate data is available

Question 13

what is important about interpretation of ecol

Answer 13

need to be careful - can easily miss important unseen info