Chapter 4 - Risk of Bias

Question 1

Explain what Cross-Sectional Studies are

Answer 1

Participants are assessed at one point in time

• Take a sample of people and ask about their status and examine them at the same time

Example: Report on difference in self physical activity in Kine Undergrads

Question 2

Pros and Cons to Cross Sectional

Answer 2

Pros: Quick and Easy, Tells you about how to move down chain of events, Gives information of relationship of variables

Cons: Can’t determine cause and effect, can’t determine temporal relations (asking them a question only one time so you can’t relate it)

Cross sectional - you collect data from the person at one point in time
* Don’t give you information over time so you don’t know if the person has changed their eating habits after the one time they told you

Question 3

What is a prospective cohort?

Answer 3

Select a group of random individuals, take baseline measures and then follow people over time (temporal relation/cause and effect can be determined)

Better than cross-sectional as it’s not a one time point, rather it’s a continous timeline you follow

Question 4

Pros and Cons of Prospective Cohort?

Answer 4

Pros: Provide measure of risk, Study many outcomes at once, Establish sequence of events

Cons: Expensive/time-consuming, not good for rare disease, loss to follow up

Question 5

Different types of bias are?

Answer 5

• Information Bias
• Selection Bias
• Mismeasurement Bias
• Confounding Bias