Psy230 2

________________ is a topic that considers the relationship between two or more variables for the purpose of prediction.

Correlation

_________________ is a measure of the extent to which paired scores occupy the same or opposite positions in their own distributions.

Pearson r

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.

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

The textbook uses the abbreviation __ _ to denote the slope of the line for minimizing errors in predicting Y .

by

A correlation coefficient expresses the ___________ and _________ of a relationship between two variables. (Remember to select two from the list).

direction magnitude

You calculate the equation for a least-squares regression line using values of X that range from 0 to 100. Based on this information, is the following statement true or false?

false

A relationship between two variables that is best described by a straight line is called a _____________ relationship.

linear

The least-squares regression line is the prediction line that ________ according to the least-squares criterion.

minimizes the total error of prediction

As the values of variable X go up, the values of variable Y go down. This is an example of a __________ relationship.

negative

The vertical distance between an observation on a scatter plot and the least-squares regression line represents ____________.

prediction error

The proportion of the variability of Y that is accounted for by X is calculated by:

r2

A measure of a line's rate of change is its ____________.

slope

Much like a standard deviation quantifies the average deviation of scores around the mean, the _________________________ provides a measure of the average deviation of the prediction errors around the regression line.

standard error of estimate

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

For any linear relationship, there is only one line that will minimize the total prediction error according to the least-squares criterion.

true

The goal of a simple linear regression is to predict (estimate) the ______________________.

value of Y based on a value of X

You find that a correlation exists between two variables. The possible causes for this correlation include (select all that are true):

variable X causes changes in variable Y the correlation between X and Y is spurious

When creating a scatterplot to illustrate a linear regression, the variable to be predicted should be placed on the ____ axis.

y

The sum of the prediction errors in linear regression equals ______.

0