Week 8 Flashcards
What is Pearson’s Correlation Coefficient?
Quantifies the linear relationship between two continuous (and normally distributed) variables. -1<r<1.
+/- = the direction of the relationship.
What is an r value?
Strength of the relationship.
Correlation coefficient
-1
0
1
-1 = Negative - downwards
0 = no correlation - everywhere
1 = Positive - upwards
When can we use Pearson’s r coefficient?
Assumes that the two variables are:
- normally distributed
- continuous
- in linear relationship with each other
What are some real life examples of positive correlations?
1) as the number of trees cut down increases, the probability of erosion increases.
2) as attendance at schools drops, so does achievement.
Real life examples of negative correlations
1) The more one works, the less free time one has.
2) As the temperature decreases, more heaters are purchased.
What is Pearson’s correlation used for?
Used to measure the strength and direction of a linear relationship between two variables.
What are stages of the r value?
Perfect, strong, moderate, weak, none.
What is coefficient of determination?
The % of variance in one variable that is accounted for by the variance in the other variable.
What is the golden rule?
- Correlation is not causation.
- Simply observe a linear relationship or not.
- To establish causality, we need to do a lot more work.
Write up results sections?
A Pearson correlation found a significant strong negative relationship between Lack of Support and Job Satisfaction, r = -.708, p = .003. We can conclude that the higher levels of support lecturers receive, the higher levels of job satisfaction they experience.
Croncach’s Alpha most commonly used?
- most commonly used when you want to assess the internal consistency of a questionnaire (or survey) that is made up of multiple Likert-type scales and items.
Cronbach’s alpha typically ranges from?
0 to 1. We want >=0.7
