Correlation 1 Flashcards
What is Correlation?
A relationship between 2 variables
What is positive association?
If one variable increases so does the other variable
What is negative association?
If one variable decreases the other variable increases
How can correlation be assess?
- Pictorially, using a scatter plot
- Numerically, using a correlation coefficient
What other association shows lack of linear association?
Curvilinear association
By looking at a scatter plot of relationship. What can we assess?
- Direction
- strength
- form
What can direction tell about relationship?
/ is positive relationship
\ is negative relationship
What can strength tell about the relationship?
The more closely bunched around the line the dots are, the stronger the relationship
What can form tell about the relationship?
If relationship is linear or non-linear (curvilinear).
How can we assess the relationship numerically?
Pearson’s r
What type of scale is needed for calculating pearson’s r?
Interval scale
How is pearson’s r calculated?
Sum all the products of the paired z-scores, then divide the result by the number of the cases minus 1.
What does the pearson’s r mean?
-1 negative relationship
0 no relationship
+1 positive relationship
How is pearsons r reported?
(r = .x, n = .x, p = .x, one-tailed)
What is the write up for reporting correlations?
A Pearson correlation was computed for the relationship between x and x. This revealed that these variables were, as predicted, x related and that the correlation was statistically significant (r = x, n = x, p = x, two tailed).
