Test 10

A researcher measures deviant behavior in a sample of 12 children from abusive homes (Test A) when they are at home and when they are at school. Another researcher measures the same behavior in a sample of 18 children from abusive homes (Test B) when they are at home and when they are at school. Which test has the larger degrees of freedom?

Test B

All other things being equal, as the sample size increases, what happens to the critical value for a related-samples t test (or for any t test, for that matter)?

The critical value decreases

Using APA notation, which value is given in parentheses when reporting the results for a t test?

The degrees of freedom

A researcher sampled 16 couples and measured the difference in their marital satisfaction. Each couple was paired and the differences in their ratings (on a 7-point scale) were taken. If the mean difference in satisfaction ratings for this sample was 1.8 ± 2.0, and the results were t(15) = 3.60, p<.01. What can be concluded about the difference in marital satisfaction?

There was a statistically significant difference in marital satisfaction.

Elementary school children spent statistically significantly more time reading in the presence of a teacher than when the teacher was absent, t(17) = 2.804, p < .05. Who are the two groups being compared in this two-tailed related samples t test?

elementary school children when the teacher is present and elementary school children when the teacher is absent

What are the ways in which participants can be matched pairs related samples t test?

experimental manipulation and natural occurrence

All other things being equal, reducing the level of significance from .05 to .01 will ______ the value of the test statistic for a related-samples t test.

have no effect on

All other things being equal, reducing the level of significance from .05 to .01 will ______ the value of the critical value for a related-samples t test.

increase

A researcher asks a sample of brothers and sisters to rate how positive their family environment was during childhood. In this study, the differences in ratings between each brother and sister pair were compared. The type of design described here is called a ______.

matched-samples design

A therapist expects that the intensity of anxiety his patients experience will decrease after they have been in therapy for 6-months. The therapist assess the intensity of the anxiety symptoms experienced by all his patients when they start therapy and after the same patients have been in therapy for 6-months. What type of related samples t test would he use to analyze the data?

pre-post repeated measures

A professor compares scores on a competency exam among students at two times during a single semester. What type of t test is most appropriate for this study?

related-samples t test

A researcher compares the difference in the amount of texting by students in class during the first week and last week of classes. The type of design described here is called a ______.

repeated-measures design

A researcher selects a sample of 41 dog owners and measures their responsiveness to pictures depicting the humane and inhumane treatment of dogs. The researcher calculates the test statistic t = 3.243. Write the result in APA notation.

t(40) = 3.24, p<.05

All other things being equal, as the degrees of freedom increase, what happens to the critical value for a related-samples t test (or for any t test, for that matter)?

the critical value decreases

A professor thinks that students will increase the number of visits they make to her office during office hours after the midterm exam compared to before the midterm exam. If the professor records the number of visits each student makes to her office before and after the midterm exam what type of related samples t test would she use to analyze the data?

within subjects repeated measures

Elementary school children spent significantly more time reading in the presence of a teacher than when the teacher was absent, t(17) = 2.804, p < .05. In this two-tailed related-samples t test, what is (are) the critical value(s)?

+2.110 and -2.110

A researcher matched 30 participants on intelligence (hence 15 pairs of participants), and then compared differences in emotional responsiveness to two experimental stimuli between each pair. For this test, what are the critical values, assuming a two-tailed test at a .05 level of significance?

+2.145 and - 2.145

A researcher records the level of attention twice from 30 students, once during an interactive portion and once during a lecture portion of class. If he computes a related-samples t test at a .01 level of significance (two-tailed test), then what are the critical values for this test?

+2.756 and -2.756

The region of rejection is larger for which value of alpha (level of significance)?

0.05

Elementary school children spent significantly more time reading in the presence of a teacher than when the teacher was absent, t(17) = 2.804, p < .05. In this two-tailed related-samples t test, how many participants were observed?

18

Elementary school children spent significantly more time reading in the presence of a teacher than when the teacher was absent, t(17) = 2.804, p < .05. In this two-tailed related-samples t test, what is the value of the test statistic?

2.804

A researcher teaches rats to recognize a specific object that by giving them their favorite treat when they touched the object. To measure their ability to recognize the specific object a week later, she records the number of times the rat touches the specific object compared to a different object. It was hypothesized that the rats would touch the specific object more than the different object to demonstrate what they learned about the specific object. If the researcher tested this hypothesis at a .05 level of significance and computes a test statistic of t = 2.842 in a sample of 28 rats, what is the degree of freedom for the test?

27

Which of the following is the correct formula to calculate degrees of freedom for the related-samples t test?

N-1

A researcher sampled 25 participants and measured their alcohol consumption (in ounces) in both a home and a bar setting. If the mean difference in satisfaction ratings for this sample was 11.4 ± 2.5 (M SD), then what is the decision and conclusion at a .05 level of significance if the test statistic t = 4.56?

Reject the null hypothesis and alcohol consumption statistically significantly different

A researcher teaches rats to recognize a specific object that by giving them their favorite treat when they touched the object. To measure their ability to recognize the specific object a week later, she records the number of times the rat touches the specific object compared to a different object. It was hypothesized that the rats would touch the specific object more than the different object to demonstrate what they learned about the specific object. If the researcher tested this hypothesis at a .05 level of significance, then what is her decision if she computes a test statistic of t = 2.842 in a sample of 28 rats?

Reject the null hypothesis.