Quiz (Chapter 10)

Inferences Concerning One or Two Means

Introduction
1. A ____ number of statistical techniques are available to researchers who want to deal inferentially with the mean(s) computed from sample data.
2.  small large
3. The technique of interval estimation can be used in studies where interest lies in one or two means.
4.  True False
Inferences Concerning a Single Mean
1. When a single sample is taken from a population, at what will the researcher be guessing, the sample mean or m?
2.  The sample mean m
3. In general, large sample sizes tend to bring about _____ confidence intervals.
4.  narrow wide
5. Look at Excerpt 10.4. Using symbols, indicate what the null hypothesis was.
6.  Ho: m = M Ho: m = 2.23 Ho: m = 35.8 Ho: m = 38.8 Ho: m = 102
7. With a single group, the null hypothesis can be rejected when the difference between the sample mean and ____ is larger than would be expected by chance.
8.  the actual population mean the pinpoint number in the null hypothesis
9. If a researcher conducts a t-test on a single group mean, and if df = 19, how many subjects were in the sample?
10.  18 19 20 It's impossible to tell based on the information given
Inferences Concerning Two Means
1. If 2 samples are "correlated," a researcher might refer to them as
2.  paired samples or independent samples. matched samples or unpaired samples. dependent samples or matched samples. Pearson samples or Spearman samples. direct samples or indirect samples
3. If two samples have different ns, this is a "tip-off" that the samples are ____ .
4.  independent correlated
5. If a group's pretest mean is compared against its posttest mean, these two sets of data are considered to be _____ .
6.  independent correlated
7. In comparing 2 means with a statistical test, 2 separate inference are made (one to m1, the other to m2).
8.  True False
9. What could you say about these two statements? (a) Ho: m1 = m2 (b) Ho: m1 - m2 = 0
10.  Neither a nor b is a legitimate null hypothesis. Only a is a legitimate null hypothesis. Only b is a legitimate null hypothesis. Both a and b are legitimate null hypotheses.
11. When comparing 2 means, Ho does not have to be set up in a "no difference" fashion.
12.  True False
13. Look at Excerpt 10.4. Which of the following statements is correct regarding the number 62 that's located inside a set of parentheses near the end of the excerpt's sentence?
14.  The number 62 is wrong; it should be 61. The number 62 is wrong; it should be 101. The number 62 is wrong; it should be 163. The number 62 is correct. It's impossible to determine whether 62 is right or wrong.
15. The means of 2 independent samples can be contrasted via a t-test, a __-test, or an __-test.
16.  v; H z; M v; F v; M z; F
17. What do the abbreviations "df" stand for?
18.  Dependence on frequencies Distribution-free Dispersion factor Descriptive fallacy Degrees of freedom
19. In an ANOVA summary table, the calculated value (i.e., F-value) is computed by dividing MSbetween by _____ .
20.  dfbetween dfwithin SSbetween SSwithin MSwithin
21. In an ANOVA summary table, the total number of subjects in both groups = dfbetween + dfwithin + ___.
22.  1 2 3 dftotal MStotal
23. In comparing 2 means via a confidence interval, suppose one end point of the CI is positive while the other end point is negative. This would indicate that there ____ a statistically significant difference between the 2 sample means?
24.  is is not
Multiple Dependent Variables
1. If a researcher has data from 2 groups on 3 dependent variables, and if he/she wants use a t-test to compare the means of the groups, how many t-tests would the researcher perform?
2.  1 2 3 5 6
3. In Excerpt 10.15, the last number in the final sentence is .008. What would this number be if there had been 2 rather than 3 disability spheres?
4.  .40 .10 .05 .025 .0125
5. The Bonferroni technique cannot be used when there's only one sample.
6.  True False
7. If the pseudo-Bonferroni technique is used by a ".05" researcher who wants to compare two groups on each of 7 dependent variables, what revised alpha level would he/she probably use?
8.  .35 .07 .05 .01 .007
Effect Size Assessment and Power Analyses
1. When conducting a test on one or two means, do most researchers do something to help them (and their readers) distinguish between statistical and practical significance?
2.  Yes No
3. In Excerpt 10.8, which number(s) should you look at if you're trying to determine whether the difference between the two means has "practical significance"?
 25.6 and 39.2 103 -9.8 .001
4. Suppose a researcher determines that 20 subjects must be in each sample in order for the statistical comparison of 2 sample means to have a power of .80.  In this study, there will be a 20% chance of a Type __ error.
5.  I II
Underlying Assumptions
1. "Randomness," "independence," and "normality" are three of the 4 underlying ssumptions associated with t-, z-, or F-tests that compare 2 means. What is the 4th underlying assumption?
2.  Equal sample sizes Equal variances Equal p-values Equal critical values
3. If a researcher tests an underlying assumption, he/she hopes to reject the assumption's null hypothesis.
4.  True False
5. In Excerpt 10.14, the results of 5 t-tests are reported.  In which of these t-tests do the sample data support most the homogeneity of variance assumption?
6.  Speed of Cognition Executive Function Episodic Memory Continuity of Attention Working Memory
7. What makes a statistical comparison of two means robust to the equal variance assumption?
8.  Equal sample sizes Equal sample means Equal sample medians Equal sample modes
1. In Excerpt 10.7, the statistical comparison of the two cohorts turned out to be "p > .05." Can the null hypothesis of the t-test be accepted, since no statistically significant difference was found?
2.  Yes No
3. The very small p-value in Excerpt 10.10 strongly suggests that all of the teachers with prior learning about whole language literacy had higher scores than did any of the teachers with no prior learning about whole language literacy.
4.  True False
5. The last sentence of Chapter 10 says: "____________ by any of these techniques, regardless of how bold the researchers' claims might be."
6.  Inferences are bound to fail Nothing is proven Valuable insights are provided Findings should be replicated

A Few Tougher Questions Over Chapter 10
1. Whereas a one-tailed test must be used whenever the null hypothesis deals with a single population, a two-tailed test must be used whenever the null hypothesis deals with two populations.
2.  True False
3. In Excerpt 10.9, if there had been 50 women and 50 men involved in the study, how many numbers in the excerpt would definitely change?
4.  1 number more than 1 number
5. In Excerpt 10.1, we are given the numerical values for the mean, the CI, and the median. Which of those numbers is definitely not right?
6.  The mean is not right; it should have been larger than 60. The CI is not right; it should have been wider. The median is not right; it should have been somewhere between 54.7 and 58.5. None of the numbers in the Excerpt is definitely wrong
7. How should the concept of "overlapping distributions" influence how we interpret the assertion in Excerpt 10.14 that "The hypertensive group had impaired performance in all measures except Continuity of Attention"?
8.  Insert "slightly" after the word "had." Insert "significantly" after the word "had." Insert "clinically" after the word "had." Insert "On average," at the beginning of the sentence.
9. If, in Excerpt 10.22, alpha had been set equal to .01 (rather than .05), the power analysis would have indicated the need for ___ patients in each group.
10.  more than 50 fewer than 50
11. If a one-way analysis of variance is used to compare 2 groups of 20 subjects each, and if the SStotal turns out equal to 86 while the MSerror turns out equal to 2, how large would the calculated value be?
12.  2 4 5 8 10
13. Look at Excerpt 10.23. In applying the Kolmogorov-Smirnov test, which of the following alpha levels would have been most "conservative" in the sense that it would have made it harder for the researchers to get a result that they wanted?
14.  .001 .05 .15