Question 1

The Mann-Whitney U test, the Wilcoxon signed rank test, and the Kruskal-Wallis test

Accepted Answer

These tests are non-parametric alternatives to traditional parametric tests, used when data do not meet the assumptions of normal distribution and equal variances. The Mann-Whitney U test compares two independent groups, the Wilcoxon signed-rank test compares two related samples, and the Kruskal-Wallis test compares three or more independent groups, all without assuming a normal distribution of the data.

Question 2

Briefly describe the different role of description in descriptive research and in causal-comparative research.

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Question 3

Name two descriptive statistics that often are calculated in a descriptive research study.

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Question 4

A researcher makes direct observations of the classroom question-asking behavior of third graders. What type of descriptive research does this study exemplify?

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Question 5

In longitudinal research, describe how samples are selected for (a) cohort, (b) trend and (c) panel studies, and provide an example of each sampling procedure.

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Question 6

Lewis Terman's study of giftedness involved repeated measurement of a panel of children identified as geniuses at various stages in their lives. What is one weakness and one strength of this study design?

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Question 7

Describe the major problem with the sampling procedure used in a cross-sectional research design, and provide an example that illustrates that problem.

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Question 8

A researcher finds a correlation between length of teaching experience (variable X) and the principal's ratings of teaching effectiveness (variable Y) for the teachers employed in the principal's school. Give two plausible interpretations of this finding.

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The answer of A researcher finds a correlation between length...

Question 9

Describe two approaches to selecting a suitable comparison group for a causal-comparative research study.

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Question 10

List three assumptions about the obtained scores in a causal-comparative study that should be satisfied in order to use the t test.

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Question 11

Under what condition should the researcher use the t test for correlated means in a causal-comparative study, and what effect will use of this type of t test have on the likelihood of finding a significant difference between groups on the variable of interest?

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Question 12

A researcher wishes to determine whether the sample's mean score on a standardized achievement test is different from the mean score of the norming group. What type of t test is most appropriate in this situation?

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Question 13

A researcher conducts a study in which 90 high school sophomores are randomly assigned to three algebra classes. Class A is taught by a lecture method, class B by a cooperative learning method, and class C by an individualized method. Algebra achievement, the dependent variable, is measured at the end of the course. What statistical significance test is most appropriate for comparing the mean algebra achievement scores of the three groups? If this test yields a value that is significant at the .05 level, how would you interpret this finding?

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Question 14

What is the major difference between analysis of variance (ANOVA) and analysis of covariance (ANCOVA)?

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Question 15

Three assumptions about population parameters should be checked when deciding to use parametric statistics to analyze causal-comparative data rather than nonparametric statistics. List one of these assumptions.

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Question 16

You have hypothesized that dogmatism is distributed among army recruits so as to approximate a normal distribution (or normal probability curve). You randomly select 1,000 recruits at a basic training center and administer the Rokeach Dogmatism Scale. Scores of the 1,000 recruits are sorted into five categories ranging from high dogmatism to low dogmatism. What statistical procedure would be most appropriate to test your hypothesis, and why?

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Question 17

Describe a suitable comparison group for each of the following defined groups in a causal-comparative study.
a. The discipline styles used by parents of high school students with high scores on an authoritarianism scale
b. The extent to which female college students who are in leadership roles in campus organizations report childhood experiences in which adults encouraged them to display leadership
c. The educational aspirations of fourth-grade Pueblo Indian boys who have attended school only on the reservation

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Question 18

Two researchers are interested in doing a study to provide descriptive information to a school district about homelessness among students attending the district's schools. One researcher is a quantitative researcher, and the other is a qualitative researcher. Assume that they are able to obtain information from school records about all the students who are categorized as homeless. Describe (a) several types of information that the quantitative researcher would be more likely to report, and (b) several types of information that the qualitative researcher would be more likely to report.

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Question 19

A researcher studies the difference in reading achievement of third-grade children who learned to read by the phonics method and those who learned to read by the whole language method of teaching reading. Children in the two groups are matched on an aptitude measure that has been found to correlate with measures of reading achievement. What type of t test should the investigator use to analyze the results, and why? If the t value is significant, what interpretation can the researcher make?

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The answer of A researcher studies the difference in reading...

Question 20

You hypothesize that low-achieving children who receive special tutoring will make significantly greater reading achievement gains than those who spend an equal amount of time engaged in solitary reading in the regular classroom. Would this hypothesis be tested with a one-tailed or a two-tailed test of significance, and why?

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Quiz 10: Nonexperimental Research Descriptive and Causal-Comparative Designs