1. The researcher's hypothesis was that the aggression levels of college students is lower than that of prisoners with life sentences. Aggression was measured by surveys given during one session. What is the null hypothesis?

a. Prisoners have higher aggression levels than college students.

b. Prisoners' aggression levels are less than or equal to college students' aggression levels.

c. There is no relationship between aggression levels and groups.

d. Prisoners' aggression levels are lower than college students' aggression levels.

2. Our assumption that population variances are equal is called the assumption of

a. homogeneity of variance.

b. pooled variances.

c. heterogeneity of variance.

d. equal effect sizes.

3. Which of the following is a reason why we may NOT find a significant difference between two groups?

a. The sample size was too small.

b. all of the other answers are reasons two means may not differ significantly

c. The variability between the groups was too large.

d. vThe true mean difference between the groups was too small.

When we have an independent sample t test, the degrees of freedom are equal to

a. (N1 - 1) (N2 - 1)

b. N1 + N2 - 2

c. N - 2

d. N - 2