Statistics 2010:
Statistics for the Social and Behavioral Sciences
Study Exercise #3
Name: __________________________
Section #: _____________
Please read the scenario for single-sample z-test and answer the following questions.
SUBMIT ANSWERS ONLINE THROUGH THE LINK ON THE COURSE WEBSITE
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Research has shown an increase in anxiety for students in statistic courses (Zeidner, 1991). You
would like to know if the anxiety level of statistic students at Auburn University is higher than
the anxiety level of college students in general. To investigate your research question, you obtain
a sample of students enrolled in statistics at Auburn University.
Please open up the Lab Dataset file located on the course website. The dataset contains several
columns of data. You will want to use the Q5, Q6, and Q7 columns. These columns represent the
ratings of three questions on an anxiety questionnaire. Each item is rated on a 7-point scale (7 =
Strongly Agree). The questionnaire items are:
Q5: I constantly feel irritable.
Q6: I feel that everything is going to be alright.
Q7: I have difficulty concentrating.
To answer your research question, you will need to compare the anxiety composite score of
statistic students to the composite score in the general population of college students. Use an
alpha of .05 (α = .05). The normed population mean for college students on the three items is
8.47 with a standard deviation of 3.45. However note that you only have ratings for each of the
three questionnaire items individually, but not the overall composite (summed) score.
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1. Before a composite score for the anxiety questionnaire can be created, you will need to
identify the questionnaire item that needs to be reverse scored (only reverse score one
questionnaire statement). Which item needs to be reversed scored?
2. Create a new variable that represents the reverse scores for the questionnaire item identified
above. Give this item the same name but add ”r” to signify that it is reversed scored.
3. Create a new variable named Comp using the summed ratings for the three questionnaire
items. Remember to use the reverse scored question as one of the three items.
4. Provide a description of the sample distribution (Note: See lecture notes. This is different than
a population distribution [description]).
5. What is the null and research hypotheses for this analysis?
6. Analyze the data in Excel using a single-sample z-test.
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7. Report the mean and standard deviation for your sample (Use “descriptive statistics” in Excel
for the composite variable [Comp]).
8. Report the z-statistic and sample size.
9. Compare the z-statistic from question 8 to the z-critical given in the output (HINT: Is this a
one or two-tailed test). What is your statistical decision?
10. Explain if instructors of statistics should be concerned about the anxiety level of students.
Consider the z-test result, test assumptions, scenario, and any additional insights in your
response.
11. Finally, save your Excel file with all of your work and submit it online via Canvas.
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