reading quiz 6 Flashcards
A relationship between two variables that is best described by a straight line is called a _____________ relationship.
linear
A measure of a line’s rate of change is its ____________.
slope
As the values of variable X go up, the values of variable Y go down. This is an example of a _________ relationship.
negative
A correlation coefficient expresses the ________ and ________ of a relationship between two variables.
magnitude | direction
_________________ is a measure of the extent to which paired scores occupy the same or opposite positions in their own distributions.
Pearson r
The proportion of the variability of Y that is accounted for by X is calculated by:
r ²
You wish to calculate correlation between two variables. One is measured on the ratio scale, the other on the ordinal scale. Which of the following approaches should be used?
Spearman rank order correlation
Which of the following best describes the effect of restricting the range of either the X or Y variable when calculating a correlation?
Restricting the range will lower the correlation coefficient.
4 answers
You find that a correlation exists between two variables. The possible causes for this correlation include (select all that are true):
- the correlation between X and Y is spurious
- variable X causes changes in variable Y
- variable Y causes changes in variable X
- a third variable is the cause of the correlation between variables X and Y
While the book covers the calculation of the Pearson r and Spearman rank order correlations, there are other types of correlations, too (e.g., the biserial and phi coefficients). The two most important considerations in selecting the proper correlation method are _____________ and _________________.
- the shape of the relationship between the two variables
- the scale(s) of measurement for the variables
