Ch 8 Lecture

Question 1

Bar Graph or Scatterplot?

Answer 1

• Focus is on measuring the variables involve
• It’s the method that makes a study correlational, not the statistic, or the type of graph

Question 2

Mediation

Answer 2

A -> C -> B; A is related to B because of C; A leads to C which leads to B; if remove C, removes A-B link; WHY are 2 variables related?

Question 3

Moderation

Answer 3

C type 1: A <–> B & C type 2: A <–(+)–> B;
A is related (more strongly) to B for one type of C but not for the other type of C; Are there certain groups or situations for which the two variables are more strongly related?

Question 4

Third-variable Problem

Answer 4

A <– C –> B; C is separately related to A and B; A and B only related but ONLY because of C; Two variables are correlated, but only because they are both linked to a third variable

Question 5

Third Variable vs Mediator; 3rd Va.

Answer 5

• Multiple regression
• Is external to the original relationship
• Relationships only exists because each variable is separately associated with the 3rd variable
• A nuisance variable (not of interest to researcher)

Question 5

Third Variable vs Mediator; Mediator

Answer 5

• Multiple regression
• Internal to the causal variable
• Which aspect of the causal variable is responsible for the outcome?
• Direct

Question 6

Moderator vs Mediator; Moderator

Answer 6

• Are these two variables linked the same way for everyone, or in every situation?
• Ex. Among wealthy people: link between conscientiousness and longevity is weak

Question 7

Moderator vs Mediator; Mediator

Answer 7

• Why are these two variables linked?
• Ex. Conscientiousness –> Healthy behaviours –> Longevity

Question 8

Example Mediator

Answer 8

Sibling aggression is associated with poor childhood mental health because child victims of sibling aggression are more likely to feel lonely at home; sibling aggression leads to loneliness, which in turn leads to mental health problems

Question 9

Example Moderator

Answer 9

Being a victim of sibling aggression is associated with poor mental health in childhood, but the link is especially strong for later-born children and weaker in first born children

Question 10

Example Third Variable

Answer 10

Sibling aggression is associated with poor childhood mental health only because of parental conflict; Sibling aggression is more likely to occur when parents argue frequently, and arguing also affects kids’ mental health

Question 11

Three Rules for Causation

Answer 11

• Covariance: is a relationship between type of object
• Temporal Precedence: what came first
• Internal validity: can you rule out possible confounds?