PS: Cohort Study Design

Question 1

What is the difference between relative risk and absolute risk?

Answer 1

Relative: when the data has been manipulated in such a way as it is a comparison of data

Absolute: the raw data

Question 2

How do you calculate IR?

Answer 2

D(exposed or unexposed) / p-y

Question 3

How do you calculate IRR?

Answer 3

Exposed IR/unexposed IR

Question 4

Name some advantages of cohort studies.

Answer 4

• You can obtain more detailed info (the could be used to collect additional data on confounding factors)
• Good at studying rare exposure
• Better at stuffing conditions that fluctuate with age
• Can establish that exposures precede outcomes

Question 5

Name some disadvantages of cohort studies.

Answer 5

• Expensive due to time and amount of resources
• Takes a long time
• Not good for rare outcomes
• Survivor bias

Question 6

Describe the process of a retrospective cohort study.

Answer 6

1. Find some exposed and unexposed individuals form the past

2. Compare and contrast the current outcomes of both groups now in the present

Question 7

Describe the process of a prospective (concurrent) cohort study.

Answer 7

1. Find some exposed and unexposed individuals form the present
2. Follow them up into the future and compare and contrast the current outcomes of both groups

Question 8

What is survivor bias?

Answer 8

When individuals do not finish the follow up due to fall down with ill health. Therefore the end data is only that of healthier individuals which counteracts the point of the survey.