Test 9

What is the value of the degree of freedom for this result t(40)=3.02 p<0.05, d=1.02, [95%CI] 1.43-10.57?

40

What is the critical value(s) for the following two-tailed t test at a 0.05 level of significance with df = infinity.

+ 1.960 and -1.960

What is the critical value for a t test using a one-tailed test at a .05 level of significance df = 30 and group 2 mean is hypothesized to be smaller than the group 1 mean.

+1.697

What is the critical value for a t test using a one-tailed test at a .01 level of significance df = 20 and group 2 mean is hypothesized to be larger than the group 1 mean.

-2.528

-A researcher compares differences in mean health scores between students at two local high schools. Assuming that the population variance is unknown, what type of t test is appropriate for this study?

-two-independent-sample t test

What is the value of the test statistic in this result, t(40)=3.02 p<0.05, d=1.02, [95%CI] 1.43-10.57?

3.02

What is the basic question being addressed by a two independent sample t test?

Are the two samples from the same population?

Which measure of effect size is most commonly reported with a t test?

Cohen's d

A researcher records the crying time (in minutes) of infants given oral administration of sucrose (n=12) or tap water (n=16) prior to a heel prick. The mean crying time in the surprise group was 3.3 +or- 2.4 (M+or-SD) min; in the tap water group, it was 7.3 +or- 1.6(M +or- SD) min. If the results is t(26)=4.05, p<0.05, what is the correct conclusion to draw regarding crying time?

Crying time was significantly reduced among infants given the sucrose solution prior to a heel prick.

A professor teaches a certain section of material using a lot of examples with sports and cars to illustrate. He is concerned that this may have biased his instruction to favor male students. To test this, he measures exam grades from this section of material among women (n=10) and men (n=10). The mean score in the male group was 84 +or- 4.0 (M+or-SD); in the female group, it was 78 +or- 8.0 (M+or-SD) points. Which of the following is the correct alternative hypothesis for this study?

Men have a higher exam grade than women

Which of the following is the correct formula to use to calculate degrees of freedom for a two independent sample t test?

N-2 (n1+n2)-2 (n1-1)+(n2-1)

Is a one sample t test reported differently for one-tailed and two-tailed tests?

No, the same values are reported.

In a two independent sample t test, what does independent mean?

Participants are in only one group The samples are not related Participants are tested once

A professor teaches a certain section of material using a lot of examples with sports and cars to illustrate. He is concerned that this may have biased his instruction to favor male students. To test this, he measures exam grades from this section of material among women (n = 10) and men (n = 10). The mean score in the male group was 84 ± 4.0 (M ± SD); in the female group, it was 78 ± 8.0 (M ± SD) points. The results of the study t(18) = 2.12, p < .05. What is the correct decision for this result?

Reject the null hypothesis

A researcher there will be a difference in productivity between employees working the morning shift (n = 16) and the night shift (n = 10). The researcher finds t(24) = 2.00, p>.05. What is the correct decision for this result?

Retain the null hypothesis

A researcher conducts two t tests. Test 1 is a one-tailed test with a smaller sample size at a .05 level of significance. Test 2 is a one-tailed test with a larger sample size at a .05 level of significance. What do you know about the critical values for each test?

Test 2 is associated with smaller critical values.

Which of the following are true for a statistically significant result?

Test statistic lies in the region of rejection

Which of the following are true for this result t(40)= 3.02 p<.05, d = 1.02, [95% CI] 1.43 - 10.57?

The result is statistically significant . The null hypothesis was rejected. The effect size is large.

A researcher thinks there will be a difference in productivity between employees working the morning shift (n=16) and the night shift (n=10). The researcher finds t(24)=2.00, p>0.05 what is the correct alternative hypothesis for this study?

There is a difference between the morning shift and the night shift on productivity.

A researcher reports that the effectiveness of a new marketing campaign statistically significantly increased sales compared with the previous campaign strategy, t(49) = 2.562, p < .05, d = .0.65. What can be concluded about the size of the effectiveness of the new marketing campaign?

There is a medium effect of the new campaign.

A professor teaches a certain section of material using a lot of examples with sports and cars to illustrate. He is concerned that this may have biased his instruction to favor male students. To test this, he measures exam grades from this section of material among women (n = 10) and men (n = 10). The mean score in the male group was 84 ± 4.0 (M ± SD); in the female group, it was 78 ± 8.0 (M ± SD) points. Which of the following is the correct null hypothesis for this study?

There is no difference between men and women on exam grades.

A researcher there will be a difference in productivity between employees working the morning shift (n = 16) and the night shift (n = 10). The researcher finds t(24) = 2.00, p>.05. What is the correct null hypothesis for this study?

There is no difference between the morning shift and the night shift in productivity.

A professor teaches a certain section of material using a lot of examples with sports and cars to illustrate. He is concerned that this may have biased his instruction to favor male students. To test this, he measures exam grades from this section of material among women (n = 10) and men (n = 10). The mean score in the male group was 84 ± 4.0 (M ± SD); in the female group, it was 78 ± 8.0 (M ± SD) points. Which of the following is the correct critical value for this study at the .05 level of significance if men are group 1?

only -1.734

Which of the following summarizes a t test that was significant and associated with a large effect size?

t(12)=2.95, p<0.05, d=0.82.

A researcher records differences in ratings of emotion among participants watching either a drama or a romance film. Assuming that the population variance is unknown, what type of t test is appropriate for this study?

two-independent-sample t test