Final practice
Part I. 统计学考试练习题代做
Short Answers – 2 points each (4)
1. A large p-value associated with test statistic will favor rejection of the nullhypoth esis.
a)True b)False
2. In a hypothesis test you assume the alternative hypothesis is true.
a)True b) False
3. These are similar measures. Why? What are they used for? Use your formula card to identify another similar measures.
4. Answer 4 out of 6 of the following question. Be precise with the language you use.
Why is the mean of one random sample a weak estimate of the population mean?
- How many random samples —drawn from a population —do you need to create a confidence interval within which you can infer with a certain level of confidence the population mean lies?
- What is the sampling distribution of means?
- When using inferential statistics to estimate an unknown population mean do you need to know all the values in the sampling distribution of means? Why or why not?
- How does alpha and the confidence level define the area in the sampling distribution you assume your random sample’s mean lies?
- What is true about your confidence interval, if in fact, your random sample (unbeknown to you) does not fall within the area set by the confidence level?
- How do we use our knowledge of the normal curve to create a confidence interval for a population mean?
Part II. 统计学考试练习题代做
Calculate and Interpret – 4 points each (5)
1.
Use the confidence interval to find the margin of error and the sample mean. (14.7,22.1)
2.
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?
3.
Use the attached SPSS output to answer the following questions.
A researcher was interested in the differences of scores on a math placement test for students who lived on campus and those who did not. They drew a random sample of 200 students and conducted an independent two population t-test.
GPA 1= Residents GPA 2= Non-Residents
- Do the data provide support for population differences in scores between the two groups? Assume α is .05.
What statistics did you use to draw your conclusion?
How is t constructed from other statistics on the output?
4.
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
5. 统计学考试练习题代做
Provide an appropriate response.
A hypothesis test for a population mean is to be performed at the 1% level of significance.
True or false: If the null hypothesis is true, the probability that the test statistic will fall in the rejection region is 0.01. 7) A) True B) False
6.
Use a table of t-values to estimate the P-value for the specified one-mean t-test.
Right-tailed test, n = 23, t = 1.571 A) 0.01 < P < 0.025 B) P > 0.10 C) 0.05 < P < 0.10 D) 0.025 < P < 0.05 1
Left-tailed test, n = 4, t = -1.527 9) A) P < 0.10 B) 0.05 < P < 0.10 C) 0.025 < P < 0.05 D) P > 0.10
Part III 统计学考试练习题代做
Application of Concepts – 6 points (5)
1.
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?
2. 统计学考试练习题代做
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
3. 统计学考试练习题代做
The Tiombe Insight Test is a psychological test designed to measure how positively a subject appraises other people. The possible scores on the test range from 0 to 41. During the development of the Tiombe test, it was given to several different groups of people.
Here are the results for random samples of college students from Northern and Southern colleges. The researchers hypothesized that this characteristic of appraisal would differ by region. Here are the results for by region.
| Group | Region | n | Mean | s |
| 1 | North | 133 | 25.34 | 5.05 |
| 2 | South | 162 | 24.94 | 5.44 |
Note: This is not a real psychological test.
Do these data support the hypothesis that Northern and Southern students differ in average measures of positive appraisal of others? (Set alpha at.05) .
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