statistics

statistics

* A criminologist rode along with patrol officers for several weeks and recorded the number of minutes they spent interviewing witnesses at a variety of crime scenes. The criminologist collected data on the number of minutes that male and female officers spent interviewing witnesses in order to examine if there are differences between men and women.

º What is the null and research hypothesis?
º If the results of the hypothesis test are t = 2.13, df = 8, and p > 0.05, how would you interpret this hypothesis test?
* Refer to the following situation and answer the questions below.

A researcher gathered data on months free of drug use for offenders released from prison. The data on seven subjects are as follows:

8 6 7 7 9 4 8

What is the range?
What is the variance?
What is the standard deviation?

* If you have a lowest score of 21 and a range of 47, what will be your highest score? Show all the steps of the calculation.

* Approximately what percent of scores fall between the mean and –1 and –2 standard deviations under the normal curve? Please provide an explanation for your answer.

14%
34%
68%
95%

* What percent of all scores fall below a z score of +1? Show all the steps of the calculation.

16%
34%
50%
84%

* In a distribution with a mean of 100 and a standard deviation of 15, what is the probability that a score will be 115 or higher? Show all the steps of the calculation.

16%
34%
50%
84%

* What is the z score for a raw score of 85 where the group mean is 75 and the standard deviation is 5?

–2.0
2.5
2.0
–2.5

* A warden is interested in the effectiveness of two different violence reduction programs to reduce violent interactions in her prison. To test for differences, the warden randomizes two groups implementing one program to each group. The amount of violent interactions per inmate is presented below. Using a = .05, perform an independent sample t-test of significance. Then answer the questions below. Show all steps of the calculations.

Program A
Program B
8
4
7
3
5
5
3
4
8
3
8
5

(t = 2.7, p < .05)

What is the null hypothesis?
What is the research hypothesis?
If t = 2.7, p < 0.05, how would you interpret this hypothesis test?

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