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Question
The degrees of freedom for a t-test for independent groups are
A. N - 1.
B. (n1 + n2) - 1.
C. (n1 + n2) - 2.
D. 2(N) - 1.
Answer
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Related questions
Q:
The value of the F-statistic in a single-factor experiment is determined by dividing the Between-Group Mean Square by the
A. Within-Group Mean Square.
B. degrees of freedom.
C. Between-Group Sum of Squares.
D. Total Sum of Squares.
Q:
Assume that the results of an F-test for a single-factor experiment are reported as: F(2, 42) = 7.30, p = .01. On the basis of this information we may conclude that there were _______ independent groups in this experiment.
A. two
B. three
C. four
D. five
Q:
When calculating Cohen's d as a measure of effect size, the difference between two means is
A. divided by the population standard deviation.
B. divided by N - 1.
C. divided by N.
D. placed in the denominator.
Q:
The _________ the value of the estimated standard error of the mean, the _________ our estimate of the population mean.
A. larger; better
B. larger; higher
C. smaller; better
D. smaller; lower
Q:
In general, the estimated standard error of the mean provides information about how well the sample mean estimates
A. the population variance.
B. the population mean.
C. the true standard error of the mean.
D. population variability.
Q:
A score that is extreme and does not "go with" other scores in the distribution is called an
A. error.
B. impossible value.
C. significant value.
D. outlier.
Q:
Computer-assisted data analysis requires that the researcher have a good knowledge of
A. null hypothesis testing.
B. research design and statistics.
C. computer hardware.
D. computer software.
Q:
A coherent "story" of data analysis for a study will include
A. an explanation of the findings.
B. counter arguments for opposing interpretations of the findings.
C. justifications for conclusions.
D. all of these
Q:
Program evaluation is a hybrid discipline whose professional activity
A. relies almost exclusively on the experimental method.
B. is confined almost entirely to the discipline of psychology.
C. has as its basic goal providing feedback to providers of human service activities.
D. focuses primarily on conducting basic research.
Q:
Researchers analyzed records of hospitalization for heart disease in two Ohio cities, Bowling Green and Kent. A city ordinance enacted in Bowling Green banned smoking in public areas. Results indicated that hospitalization rates for the two cities were similar before the smoking ban, but hospitalization rates decreased in Bowling Green compared to Kent following the smoking ban. A potential threat to internal validity that will need to be ruled out is
A. the amount of information about heart disease presented in national media.
B. changes in the state sales tax on cigarettes.
C. changes in doctors' focus on symptoms of heart disease in Bowling Green (because of publicity for the ban), but not in Kent.
D. all of these
Q:
The major threat to internal validity in the simple interrupted time series design is
A. history.
B. maturation.
C. selection.
D. additive effect of selection and history.
Q:
If the residents, staff, and facilities of a nursing home where a quasi-experiment was done are likely to be different from those in other nursing homes, the ______________ of the findings may be questioned.
A. external validity
B. statistical significance
C. internal validity
D. novelty
Q:
One threat to the internal validity of research that affects both true experiments and quasi-experiments is
A. selection threats.
B. additive effects with selection.
C. experimenter expectancy effects.
D. all of these
Q:
A threat to internal validity that occurs when information about the experiment is communicated between the different groups of participants is known as
A. expectancy effects.
B. contamination.
C. novelty effects.
D. the Hawthorne effect.
Q:
Lab-based experiments are likely to have greater _________, and experiments in natural settings are likely to have greater __________.
A. social application; theoretical implications
B. internal validity; external validity
C. consequences for more people; control
D. all of these
Q:
The external validity of research done in natural settings is likely to be emphasized more when the research represents
A. an experiment done to address a specific question raised by a specific company.
B. an extension of a specific laboratory finding.
C. social experimentation as the basis for large-scale changes.
D. a theoretically motivated social psychology experiment.
Q:
A psychologist develops a behavioral treatment to decrease the frequency of a child's temper tantrums. In order to make a causal interpretation about the effectiveness of the treatment using an ABAB design, the most problematic initial baseline period would show
A. a stable pattern of temper tantrums.
B. a greater number of temper tantrums in the baseline period compared to the treatment period.
C. an increasing trend in the number of temper tantrums.
D. a decreasing trend in the number of temper tantrums.
Q:
Problems in the interpretation of the results of a multiple-baselines design can arise when
A. changes in performance appear in one of the baselines after an experimental intervention.
B. changes in performance appear in one of the baselines before an experimental intervention.
C. changes in performance appear in the treatment stage simultaneously with an experimental intervention.
D. changes in performance appear in the treatment stage after an experimental intervention.
Q:
In a multiple-baseline design, the target behavior should change
A. just before the onset of the treatment.
B. long before the onset of the treatment.
C. just after the onset of the treatment.
D. long after the onset of the treatment.
Q:
Which of the following is not a source of bias in case studies?
A. testing clinical innovations
B. socially desirable responses in a client's report of his or her behaviors
C. distortions in the client's memory for past events
D. inaccuracies in the therapist's observations of the client's behavior
Q:
The major difficulty with the case study method as a basis for drawing cause-and-effect conclusions is that
A. coding of the results cannot be done reliably and validly.
B. the simultaneous use of several treatments and failure to control extraneous variables prevent causal inference.
C. excessive constraints on the external validity of the case study prevent causal inference.
D. biases of the researcher must dominate the interpretation of the results.
Q:
Case studies have been used successfully to study individuals with brain disorders and individuals with exceptional memory abilities. These studies illustrate the use of the case study method to
A. apply the nomothetic approach.
B. test a clinical innovation.
C. provide conclusive evidence for a particular theory.
D. study rare phenomena.
Q:
Suppose the following data were observed for an individual who sought treatment for kleptomania. Using a single-case experiment, the psychologist used "covert sensitization" to treat the stealing behavior across a number of different situations (e.g., stealing at the grocery store, drug store, discount store). Covert sensitization was applied systematically to each situation. The psychologist concluded that the treatment was very effective for reducing kleptomania.
As shown in the following graphs, an initial baseline period was conducted for each of three situations. The session in which covert sensitization was implemented is indicated with each situation (session 3, 6, or 9). The dependent variable is the number of shoplifted items.
What type of research design was used in this study? [Be specific.]
Q:
(p. 292-294, 297) Identify a methodological problem specific to the ABAB design and a methodological problem specific to the multiple-baseline designs.
Q:
(p. 290, 297-299) Describe an advantage and a disadvantage of single-case experimental designs relative to multiple-groups designs.
Q:
When each level of one independent variable is combined with each level of a second independent variable, the combination of these two variables is called
A. a complete design.
B. counterbalanced combination.
C. an interaction effect.
D. factorial combination.
Q:
(p. 244-245, 247) A researcher examined whether interrogators who expect a suspect to be guilty, rather than innocent, use more persuasive interrogation techniques. The researcher created a laboratory situation in which students were randomly assigned to actually commit a crime or not commit a crime by following a set of instructions given to them. This is referred to as "Suspect Status." Before student interrogators interviewed a suspect, they were randomly assigned to conditions that led them to believe the suspect was guilty or innocent of the crime. This is referred to as "Interrogator Expectation." Independent observers rated the effort used by interrogators to obtain a confession using a 1-10 rating scale (higher scores indicate greater effort). Suppose the researcher observed the following means for each group:
Q:
(p. 244-245, 247) A researcher was interested in the effects of arousal and personality on individuals' GRE test performance. The personality variable he examined was individuals' level of introversion-extraversion. Based on questionnaire responses, each participant was classified as an "extravert" or an "introvert." The researcher manipulated arousal level by giving caffeine to participants prior to administering a practice GRE test. Participants were randomly assigned to a high-caffeine condition, a medium-caffeine condition, or the no-caffeine condition. All participants then completed a version of the quantitative portion of the GRE.
Suppose the researcher observed the following means for each group:
Q:
A researcher conducts a study to determine if the variable of test anxiety influences performance on two types of GRE tests, the verbal and quantitative tests. He uses a questionnaire to assess individuals' test anxiety and classifies participants as high test anxious (n = 40) or low test anxious (n = 40). He is also interested in knowing whether high or low test-anxious individuals' performance is different for the computerized version of the two tests compared to the paper-and-pencil version of the tests. Within each anxiety group, he randomly assigns participants to either the computer version or the paper version of the GRE tests. Participants then complete both the verbal and quantitative tests of the GRE in the test version they've been assigned (computer or paper). Thus, each participant has two scores, a Verbal score and a Quantitative score.
Assume the following results were observed for the mean Verbal scores (we'll ignore Quantitative scores):
Based on these findings, the researcher claims that Test Version, computer vs. paper, does not affect individuals' average performance. What information is the researcher using to make this claim? Is this claim justified?
Q:
When an independent variable such as task difficulty has been shown to interact with a second independent variable such as age, the generality (i.e., ability to generalize the findings) of the effect of the task difficulty variable is
A. complete.
B. unaffected.
C. limited.
D. increased.