Exam 9: The T Test for Independent Means

Suppose you carry out a study using a t test for independent means. The number of participants in each group is 50 and you conduct a two-tailed test. What would be the approximate level of power if you anticipated a small effect size? (Consult the power table 9-4.)

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

For the following question(s): A sociologist interested in cultural differences compared women of two ethnic groups on a Role Approval Index (high scores mean high degrees of approval of one's 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 you conduct a t test for independent means, how many degrees of freedom are in the t distribution?

In the formula [t = M1-M2 /S_Difference], "S_Difference" is:

One of the assumptions for the t test for independent means is that:

"S²_Pooled / N₁" is the formula to find the variance of the __________ for Population 1.

The __________ is used to compare scores from __________.

When using a t table, the degrees of freedom you should use for a t test for independent means is the:

The effect size for the t test for independent means is the difference between the sample means divided by the:

A health researcher conducted an experiment in which participants watched a film that either did or did not include a person being injured because of not wearing a seat belt. A week later, as part of a seemingly different study, these same participants reported how important they thought it was to wear seat belts. The 16 participants who had seen the injury film gave a mean rating of 8.9 with an estimated population standard deviation of 2.1. The 36 participants in the control condition had a mean of 7.0 with an estimated population standard deviation of 2.4. Do these results suggest that seeing a movie with a person being injured due to not wearing a seat belt makes attitudes more positive (higher ratings)toward seat belt usage? (Use the .01 level.) a. Use the five steps of hypothesis testing. b. Sketch the distribution involved. c. Figure the effect size. d. Explain what you did to a person who is familiar with the t test for a single sample but is unfamiliar with the t test for independent means.

When determining the pooled population variance estimate in a t test for independent means:

In a single-sample t test, suppose the mean of your sample 1 is 90, the mean of Population 2 is 75, and the standard deviation of the distribution of differences between means is 6. What is the t score?

In an experiment involving 50 participants, which study would have the most power?

Which of the following is an example of a situation in which you could conduct a t test for independent means?

In a t test for independent means, when the number of scores in the two groups differs, the __________ is used as the equivalent of each group's sample size when determining power.

When sample sizes are unequal, the __________ tells you the equivalent size that two equal-sized samples would need to be for a study to have the same amount of power.

In the formula" = S²M₁ + S²M₂" the "S²M₁" is:

A study has 18 participants in the experimental group and 7 participants in the control group. What is the harmonic mean of these sample sizes?

The variance of a distribution of differences between means equals:

Each of the following is part of conducting a t test for independent means, EXCEPT: