P-values
What does “statistical significance” mean?
The results are unlikely to have occurred by chance.
What does Pearson’s r measure?
The strength and direction of a linear relationship.
What is a main effect?
The effect of one independent variable.
If we have a continuous dependent variable, should we use a linear or logistic regression analysis?
Linear
p = .03 — what decision should the researcher make? reject or retain the null hypothesis
Reject the null hypothesis.
If p = .10, is the result statistically significant?
No, it is above .05
What does a positive r mean?
As one variable increases, the other tends to increase.
What is an interaction?
When one variable’s effect depends on the level of another variable.
What kind of outcome does logistic regression predict?
a dichotomous outcome (e.g., yes/no; depressed/not depressed)
r = .25 — Describe and draw the relationship.
Weak, positive relationship
What does a p-value of .03 mean?
There’s a 3% chance the results occurred due to chance.
What does r = 0 mean?
No linear relationship between the two variables.
How many independent variables are in a 2x2x2 factorial design AND how many levels are in each?
3
2 levels each
What does an OR > 1 mean?
Higher odds of the outcome happening.
A 2×2 factorial design finds a main effect for gender but no interaction. What does that mean?
Gender influences the DV regardless of the other variable.
What does “fail to reject the null hypothesis” mean?
There’s not enough evidence to say there’s an effect.
r = –.80; draw this relationship
Strong, negative relationship.
In a 3×2 design, how many main effects are possible?
Two (one per independent variable).
What does a β (beta) coefficient show?
How strong the predictor is, compared to other predictors.
OR = 3.0 for stress predicting anxiety. Interpret.
Interpret.High stress triples the odds of anxiety.