Essentials of Statistics for the Behavioral Sciences, 8th Edition solutions manual and test bank by Frederick J Gravetter | Larry B. Wallnau
Solutions for
End-of-Chapter Problems
Note: Many of the problems in the text require several stages of computation. At each stage there is an opportunity for rounding answers. Depending on the exact sequence of operations used to solve a problem, different individuals will round their answers at different times and in different ways. As a result, you or your students may obtain answers that are slightly different from those presented here. To help minimize this problem, we have tried to include the numerical values obtained at different stages of complex problems rather than presenting a single final answer.
Chapter 1: Introduction to Statistics
1. a. The population is the entire set of adolescent boys who take medication for depression.
b. The sample is the group of 30 boys who were tested in the study.
2. The population is the entire group of individuals (or scores) of interest for a particular research study. A sample is a group selected from a population that usually is used to represent the population in a research study. A parameter is a characteristic, usually a numerical value, that describes a population. A statistic is a characteristic, usually numerical, that describes a sample.
3 Descriptive statistics are used to simplify and summarize data. Inferential statistics use sample data to make general conclusions about populations.
4. Sampling error is the naturally occurring difference between a sample and the population from which the sample is obtained. Specifically, the statistics obtained for a sample will be different from the corresponding parameters for the population and the statistics will differ from one sample to another. This is a problem for inferential statistics because any difference found between two treatment conditions may be explained by the treatments but it also may be explained by sampling error.
5. A correlational study has only one group of individuals and measures two different variables for each individual. Other research evaluating relationships between variables compares two (or more) different groups of scores.
6. The goal of an experiment is to demonstrate the existence of a cause-and-effect relationship between two variables. To accomplish the goal, an experiment must manipulate an independent variable and control other, extraneous variables.
7. The independent variable is the amount of control over office design. The dependent variables are productivity and well-being.
8. This is not an experiment because no independent variable is manipulated. They are comparing two preexisting groups of individuals.
9. a. This is a nonexperimental study. The researcher is simply observing two variables. No
variable is manipulated to create the two groups.
b. This is an experiment. The researcher is manipulating the amount of vitamin C and
should control other variables by using equivalent groups of participants.
10. a. The dependent variable is comprehension of the passage, which is measured by the test
scores.
b. Knowledge or comprehension is continuous.
c. ratio scale (zero means no correct answers)
11. This is not an experiment because there is no manipulation. Instead, the study is comparing two preexisting groups (state university and religious college students).
12. The independent variable is the substance that is inhaled, either oxytocin or the inactive placebo. The dependent variable is how likely the people were to give their money to the trustee.
13. a, Time is continuous.
b. Discrete
c. Discrete
d. The underlying variable is knowledge, which is continuous.
14. a. An ordinal scale provides information about the direction of difference (greater or less) between two measurements.
b. An interval scale provides information about the magnitude of the difference between two measurements.
c. A ratio scale provides information about the ratio of two measurements.
15. a. The independent variable is Tai Chi versus no Tai Chi (control).
b. The independent variable is measured on a nominal scale.
c. The dependent variable is the amount of arthritis pain.
d. The dependent variable is measured on an interval or ratio scale.
16. Shyness cannot be observed directly like height or eye color. Instead, it is a hypothetical construct, which is an internal attribute or characteristic that cannot be observed directly. Shyness could be operationally defined by recording specific behaviors in a social situation or with a questionnaire asking about behaviors and attitudes.
17. a. The independent variable is whether or not the motivational signs were posted, and the dependent variable is amount of use of the stairs.
b. Posting versus not posting is measured on a nominal scale.
18. a. SX = 10
b. SX2 = 38
c. SX + 1 = 11
d. S(X + 1) = 14
19. a. SX2 = 48
b. (SX)2 = 142 = 196
c. S(X – 1) = 9
d. S(X – 1)2 = 25
20. a. SX = 0
b. SX2 = 50
c. S(X + 3) = 15
21. a. SX = 4
b. SY = 18
c. SXY = 11
22. a. Σ(X + 1)
b. Σ(X + 1)2
c. (ΣX)2 – 3
23. a. SX2 = 50
b. (SX)2 = 122 = 144
c. S(X – 3) = 0
d. S(X – 3)2 = 14
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