Ch 8 stat

A social psychologist interested in cultural differences compared women of two ethnic groups on a Role Approval Index on which high scores indicated high degrees of approval of one's own social role. The results were as follows. Ethnic Group A: N = 15 M = 55 S2 = 6.5 Ethnic Group B: N = 23 M = 51 S2 = 4.5 If a t test for independent means is conducted, how many degrees of freedom will be used to locate the cutoff score in the t table?

(15 - 1) + (23 - 1) = 36

The most common way for a t test for independent means to be reported in a research article is

t (45) = 3.5, p < .05

The comparison distribution for a t test for independent means is a t distribution instead of a normal curve because

the population variance is estimated

Which statement is only true for the t test for dependent means rather than t tests in general?

Pretest-posttest experimental designs are common.

Which of the following is the MOST serious violation of an assumption for the t test for independent means?

The populations are dramatically skewed in opposite directions.

In which of the following situations would a t test for independent means be conducted?

a comparison of scores of participants in a memory study where one group is assigned to learn the words in alphabetical order and another group is assigned to learn the words in order of length of the word

The comparison distribution for a t test for independent means is a

distribution of differences between means.

The best way to reduce the variances in the distributions of means when conducting a t test for independent means is to

increase the size of the samples.

An experimenter hypothesizes that biology majors score higher than literature majors on an intelligence test. If the mean score for biology majors was 18.8 and the mean score for literature majors was 21.3, and the Sdifference was 0.9, the t score was

t = (18.8 - 21.3) / 0.9 = -2.78

Based on the following results, which would be the correct use of the formula, t = (M1 - M2) / Sdifference? Sample 1: Mean = 60; Variance of the distribution of means = 2 Sample 2: Mean = 50; Variance of the distribution of means = 7

t = (60 - 50) / √(2+7)

A "distribution of differences between means" can be thought of as a distribution of

the differences obtained when a sample mean from one population is repeatedly subtracted from a sample mean from another population.

When figuring the pooled population variance estimate in a t test for independent means,

the estimates based on each of the samples are averaged in such a way as to give more influence to the estimate based on more participants.

When conducting a t test for independent means, a typical research hypothesis might be

the mean of Population 1 is greater than the mean of Population 2.

If an experimenter conducts a t test for independent means and rejects the null hypothesis, the correct interpretation is that

the mean of one sample is so far from the mean of the other sample that the samples must come from populations with different means.

A t test for independent means is reported as "t (28) = 4.21, p < .01." This means

the t score was 4.21.