Practice Worksheet for Final Exam
1. What are the two types of statistical inference?
a.
b.
2. You draw a sample of 225 inmates from a prison. You find that the average
number of arrests among inmates in your sample is 9, and the standard deviation
is 3. Using this data to illustrate your answer, tell me what statistical inference is,
and how parameter estimation works. Make sure you cover the following
concepts in your answer:
a. sample,
b. point estimate,
c. interval estimate,
d. level of confidence,
e. sampling distribution,
f. standard error of the mean,
g. population
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3. When talking about statistical inference, what is alpha? What are the typical sizes
of alpha? What does it mean?
4. You want to test the following hypotheses. What type of statistical test do you
run? Why do you run this test (what can you tell from it?)
a. Research hypothesis #1: Males have a higher mean level of income than
females. Income is measured in thousands of dollars earned per year.
b. Research hypothesis #2: Males are more likely to be alcoholics than
females. “Alcoholic” is coded “yes/no.”
5. Calculate chi-square using the following information:
225 males had high stress occupations, 40 males had low stress occupations, 300
females had high stress occupations, 60 females had low stress occupations.
6. The SPSS output sheets for this question shows a crosstabulation of the variables
SEX (gender) and GRASS (attitude towards marijuana), taken from a random
sample of Americans. Both variables are coded as shown in the table. Using the
information presented to you, do the following:
a.
b.
c.
d.
Identify the independent and dependent variable.
State a plausible research hypothesis for these two variables.
State the null hypothesis.
Test the null hypothesis and make a decision, reporting the information
you used to make that decision.
e. Interpret the results.
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7. The SPSS output sheets for question 7 adds a 3rd (or control) variable to test the
relationship between SEX and GRASS. The 3rd variable is FUND
(fundamentalism of respondent’s religion) with values coded as indicated. Using
the research and null hypotheses you constructed for question 6:
a. Test the null hypothesis using the SPSS with the 3rd variable and make a
decision, reporting the information you used to make that decision.
b. Interpret the results.
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8. Give an example of a variable. Identify values of this variable.
9. Give TWO examples of units of analysis – make them different from each other.
Understand how a unit of analysis differs from a variable, and from the values of
a variable.
10. What are three measures of central tendency?
a.
b.
c.
11. Income can be measured on several levels. Describe how income could be
measured as an ordinal, interval and ratio measure.
a. Ordinal
b. Interval
c. Ratio
12. Which of the following alternative hypotheses is worded correctly, given the
following information: The independent variable is gender, and the dependent
variable is income (level of measurement: ratio). Group 1 is males and Group 2 is
females. It is the land of Wazu, where men’s liberation is an uphill battle. You
expect males to have a lower mean income than females.
A. The difference between the mean income of males subtracted from the
mean income of females is less than zero.
B. The difference between the mean income of females subtracted from the
mean income of males is less than zero.
C. The difference between the mean income of females subtracted from the
mean income of males is more than zero.
D. None of the above.
(Hint: Draw a normal curve if it helps…..)
13. Describe what variance is in terms of means (including drawing examples of
normal curves) and why a Levene’s test statistic is use.
14. In the SPSS output sheets you will find output for the difference between means
for respondent’s mothers’ level of education (MAEDUC) by whether the
respondent is male or female (SEX). The data is taken from a random sample of
Americans. MAEDUC is measured in terms of years. Use your knowledge and
the information below to do the following:
a) Write a plausible research hypothesis about the relationship between these two
variables.
b) State the null hypothesis.
c) State the alternative hypothesis.
d) Determine if you are doing a one- or two-tailed test.
e) Using information from the SPSS output, draw a graph indicating the side of
the normal curve on which the values of the independent variable are located.
f) Test the null hypothesis and make a decision, reporting the information you
used to make that decision.
g) Interpret the results.
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