Quiz 3

The value of a Pearson's r ranges between

-1.0 - 1.0

You find a correlation between creativity and academic honesty of r= -.40. The coefficient of determination for this relationship is:

.16

What is the degrees of freedom is N = 7?

5

After a study that assessed the anxiety of students before Research Methods test, the researcher reports that all the students scored between 20 and 25 on the 25 point scale of anxiety. What problem might exist with the scale?

Ceiling effect

The more scattered the points on a scatterplot, the stronger the relationship between variables (T/F)

False

After computing a correlation, we compare our computed r value to the critical values for Pearson's r using ______ degrees of freedom.

N-2

_______ is a measure of the strength of a linear association between two variables and is denoted by r.

Pearson correlation

You believe that students' anxiety is related to test scores in Research Methods. Which of the following represents a directional alternative hypothesis for your study?

Students' anxiety will be negatively related to their test scores in Research Methods

A correlation of -.52 represents a stronger relationship than a correlation of .35 (T/F)

True

Correlational designs are sometimes used when variables cannot ethically or feasibly be manipulated. (T/F)

True

One of the reasons why correlation does not equal causation is because there is the probability that a third variable is responsible for the relationship (T/F)

True

The close the absolute value of a Pearson's r is to the absolute value of 1.0, the stronger the relationship between two variables. (T/F)

True

The point-biserial correlation (rpb) is used to analyze the

correlation between a dichotomous and interval/ration variable

We want our computed r value to be ______ the critical value listed in the table in order for it to be significant.

greater than

The strength of the relationship is evident from ______, and the direction of the relationship is evident from ______ in a correlation coefficient.

how close the correlation coefficient is to the absolute value of 1.0; the sign of the coefficient

Anne and Jack are examining variables related to self control. Anne finds r= .35 between percentage salary saved and self control while Jack finds r= -.50 between impulsivity and self control. Which variable is more strongly correlated to self control?

impulsivity

The image in this scatterplot represents:

negative correlation

When two variables move in opposite directions (one increases while the other decreases), they are

negatively correlated

You want to examine the relationship between owning a house (yes-no) and income. You would complete a

point-biserial correlation coefficient

A correlation coefficient provides two pieces of information about a relationship. They are the

strength and direction of a relationship