Summer 2022_Final Practice
Part I. Short Answers – 2 points each (4) 统计学期末代考
1.These are similar measures. Why? What are they used for? Use your formula card to identify another similar measure.
2.A large p-value associated with test statistic will favor rejection of the null hypothesis
a) True b) False
3.In a hypothesis test you assume the alternative hypothesis is true.
a) True b) False
Part II. Calculate and Interpret – 4 points each (5) 统计学期末代考
4.
Use the confidence interval to find the margin of error and the sample mean. (14.7,22.1)
5.
A researcher is interested in understanding the difference between children and adults’ perception of the severity of an illness.
He draws a random sample of children, the child sample, from the hospital with a major illness. The children’s parents have agreed to their children’s participation in the study.
He then constructs a second sample, the adult sample, by identifying either one or both parents of the child. He administers a perception of severity of illness measure to the child and adult sample and examines differences in the measure. (He averages the scores when the child has two active parents.
Are the child and adult samples paired or independent samples?
6.
A personnel researcher has designed a questionnaire she believes will take an average of 35 minutes to complete. Suppose she samples 20 employees and finds that the mean time to take the test is 27minutes with a standard deviation of 4 minutes. Determine if there is sufficient evidence to conclude that the completion time of the newly designed test differs from its intended duration. Conduct the test at the .05 level.
State the null hypotheses
7. 统计学期末代考
A sample mean, sample standard deviation, and sample size are given. Use the one-mean t-test to perform the required hypothesis test about the mean, μ, of the population from which the sample was drawn. Use the P-value approach. Also, assess the strength of the evidence against the null hypothesis.
X bar =137, s=14.2,n=20,H0:μ=132,Ha:μ1 does not equal 32, alpha = 0.1
A) Test statistic: t = 1.57. P-value = 0.0582. Reject H0. There is sufficient evidence to conclude that the mean is different from 132. The evidence against the null hypothesis is moderate.
B)Test statistic: t = 1.57. P-value = 0.1164. Do not reject H0. There is not sufficient evidence to conclude that the mean is different from 132. The evidence against the null hypothesis is weak or none.
C)Test statistic: t = 1.57. P-value = 0.0659. Reject H0. There is sufficient evidence to conclude that the mean is different from 132. The evidence against the null hypothesis is moderate.
D)Test statistic: t = 1.57. P-value = 0.1318. Do not reject H0. There is not sufficient evidence to conclude that the mean is different from 132. The evidence against the null hypothesis is weak or none.
Part III Application of Concepts – 6 points (5) 统计学期末代考
8.
The Health Department of a Major City claims the mean time it takes smokers to quit permanently is 15 years, with a standard deviation of 6.2 years.
You have a random sample of 32 former smokers
Your analysis results in a z-score of -.15.
- What was the average length of time it took your sample to quit smoking permanently?
- At the .05 level is there enough evidence to reject the claim that it takes smokers 15 years to quit permanently?
9. 统计学期末代考
A mental health researcher is interested if group therapy online where is beneficial to patients diagnosed with a major depressive episode. She randomly selects 40 patients from a population of patients in a university hospital who agree to participate in the study and have been diagnosed with a major depressive episode. Twenty of the patients are randomly assigned to a group which receives group therapy sessions online one day per week. The other 20 patients are offered weekly one-on-one therapy online or in person with an experienced provider. Time to relapse is measured in years.
| N | X-bar | s | |
| Group Therapy | 20 | 3.8 yrs | .6 |
| Individual Therapy | 20 | 2.0 yrs | .5 |
T = 10.307 where pooled p = .305
