What three conditions must be present in order to establish ...

[RODY.ELKHALIL]

What three conditions must be present in order to establish causality?
 
  What will be an ideal response?

Question 2

Briefly compare the different functions of cross-sectional designs and longitudinal designs.
 
  What will be an ideal response?

[LP]

Answer to Question 1

In order to establish causality, three conditions must be present. First, if A is the causal variable under question, then A the cause and B the effect variables must be correlated. Second, A must precede B in time. Third, other potential causal variables, C, must be ruled out.

Answer to Question 2

Different types of research designs each can contribute different things to our understanding of causal relationships. A type of study called a cross-sectional design observes several cohorts (groups with similar defining characteristics) by taking a snapshot of them at a given point in time whereas longitudinal designs track cohorts over time taking multiple snapshots.