Question

A school counselor in a high school would like to try out a new conflict-resolution program to change aggressiveness in students. She first surveyed 16 students using a 20-item instrument to measure their levels of aggression (on a scale of 0 to 10, with higher numbers meaning higher aggression levels). One month after the conflict resolution program was implemented, the students were given the same survey. The data are listed in the table below. The school counselor/researcher has set the significance level at α = .05.

What are the independent and dependent variables?

Group of answer choices

IV: level of aggression; DV: conflict resolution program (pre- vs. post-)

IV: level of conflict resolution skills; DV: level of aggression

IV: conflict resolution program (pre- vs. post-); DV: level of aggression

IV: level of aggression; DV: level of conflict resolution skills

Question 2

The researcher does not specify if the aggression scores will increase or decrease after the conflict resolution program. Identify the null hypothesis for this two-tailed test:

Group of answer choices

Levels of aggressiveness are not different after the conflict resolution program.

Levels of aggressiveness are different after the conflict resolution program.

Levels of aggressiveness do not decrease after the conflict resolution program.

Levels of aggressiveness decrease after the conflict resolution program.

Question 3

The data for this study are presented below. Compute the difference scores by subtracting the before scores from the after scores (in other words, after-before), and then find the mean of the difference scores. (Round to two decimal places.)

Question 4

Calculate the variance of the difference scores. (Round to two decimal places.)

Question 5

Calculate the standard error. (Round to 2 decimal places.)

Question 6

Calculate the t statistic for the sample. (Round to 2 decimal places.)

Question 7

Because the hypotheses are non-directional, a two-tailed test can be performed. Determine the critical t value based on the degrees of freedom and the preset .05 alpha level.

Group of answer choices

+1.96, -1.96

-2.132

+2.132, -2.132

+1.96

Question 8

What is the hypothesis test result based on the comparison of the t statistic and the critical t value?

Group of answer choices

Fail to reject the null hypothesis because the calculated t statistic is less extreme than -2.132.

Reject the null hypothesis because the calculated t statistic is more extreme than -2.132.

Fail to reject the null hypothesis because the calculated t statistic is more extreme than -2.132.

Reject the null hypothesis because the calculated t statistic is less extreme than -2.132.

Question 9

Based on the hypothesis test result, which of the following is the answer to the research question?

Group of answer choices

Level of aggression after the conflict resolution program is significantly lower than aggressiveness scores before the conflict resolution program.

Level of aggression after the conflict resolution program is not significantly different than aggressiveness scores before the conflict resolution program.

Level of aggression after the conflict resolution program is not significantly different than aggressiveness scores before the conflict resolution program.

Level of aggression after the conflict resolution program is not significantly lower than aggressiveness scores before the conflict resolution program.

Question 10

Is it appropriate to conduct Cohen’s d test of effect size in this case?

Group of answer choices

Yes

No

Answer 1

1)
IV: conflict resolution program (pre- vs. post-); DV: level of aggression

2)
Null hypothesis always contains equality
Levels of aggressiveness are not different after the conflict resolution program

7)
TS = t.inv.2t(alpha, df)   {in excel}
here alpha = 0.05
df =n-1   for paired t-test

as this is two-tailed, there will be two critical values
+2.132, -2.132

8)
we reject the null if |TS| > critical value
here critical value = 2.132

hence answer will one of
Fail to reject the null hypothesis because the calculated t statistic is less extreme than -2.132.
or
Reject the null hypothesis because the calculated t statistic is more extreme than -2.132

depending on magnitude of TS

Image is not uploaded properly {hence Q3-Q6 is not answered, all values can be found in image though}
please post rest questions again