Psych 200: Research Methods and Statistics Chapter 9 Review

3. When the dependent variable is measured both before and after manipulation of the independent variable, we are using a __________ design.

Pretest/ Posttest Control Group Design

2. When we use __________, we randomly determine who serves in each group in an experiment.

Random Assignment

()9. When the measuring device is limited in such a way that scores at the top of the scale cannot be differentiated, there is a __________ effect.

Ceiling Effect

13. __________ is an inferential statistic for measuring effect size with t tests

Cohen's d

11. When a study is based on another study but uses different methods, a different manipulation, or a different measure, we are conducting a __________ replication.

Conceptual Replication

12. A(n) __________ is a parametric inferential test for comparing sample means of two independent groups of scores

Independent-Groups t test

6. If there is a problem with the measuring device, then there may be a(n) __________ effect.

Instrumentation Effect

4. __________ is the extent to which the results of an experiment can be attributed to the manipulation of the independent variable, rather than to some confounding variable.

Internal Validity

3. What are Internal Validity and External Validity, and why are they so important to researchers?

Internal Validity has to do with the internal workings of the study, in other words, whether or not the study is well designed. A study with internal validity has no confounds. External Validity has to do with the generalizability of a study. For example, was a random sample used so that results can be generalized to the population?

5. A(n) __________ is a threat to internal validity where the possibility of naturally occurring changes within the subjects is responsible for the observed results.

Maturation Effect

1. An experiment in which different subjects are assigned to each group is a __________.

Between-Subjects Design

The extent to which the results of an experiment can be generalized is called __________.

External Validity

2. On the most recent exam in your biology class, every student earned an A. The professor claims that he must be a really good teacher for all of the students to have done so well. Given the confounds discussed in this chapter, what alternative explanation can you offer for this result.

1. A's could be a result of an Instrumentation Effect, meaning that there may have been a technological failure in the grading process. 2. A's could be a result of an Experimenter Effect, meaning the professor may have been biased (consciously or unconsciously) and unjustly given students higher scores. 3. A's could be a result of a Selection Bias, meaning that the students may have simply been smarter than others.

1. You read in a health magazine about a study in which a new therapy technique for depression was examined. A group of depressed individuals volunteered to participate in the study, which lasted 9 months. There were 50 subjects at the beginning of the study and 29 at the end of the 9 months. The researchers claimed that of those who completed the program, 85% improved. What possible confounds can you identify in this study?

1. There was no control group in the study. Only one group was examined 2. There was a high Attrition (mortality) rate. It is possible that those who dropped out of the program were not being helped by the treatment. Thus, had they remained the improvement rate would not have been so high. 3. There are also possible history or maturation effects at play. History Effects could be due to some external event or policy. The 9 month duration of the study accounts for the Maturation Effect.

()7. If the subjects talk to each other about an experiment, then there may be __________.

Diffusion of Treatment

8. When neither the experimenter nor the subject has been assigned, a __________ experiment is being used.

Double-Blind

12. The value of the t test will __________ as sample variance decreases a. increase b. decrease c. stay the same d. not be affected

a. increase

1. Manipulate is to measure as __________ is to __________. a. independent variable; dependent variable b. dependent variable; independent variable c. control group; experimental group d. experimental group; control group

a. independent variable; dependent variable

tcv = 2.15 and tobt = -2.20. Based on these results we a. reject Ho b. fail to reject Ho c. accept Ho d. reject Ha

a. reject Ho

13. Which of the following t tests results has the greatest chance of statistical significance? a. t(28) = 3.12 b. t(14) = 3.12 c. t(18) = 3.12 d. t(10) = 3.12

a. t(28) = 3.12

5. Joann conducted an experiment to test the effectiveness of an antianxiety program. The experiment took place over a 1-month time period. Subjects in the control group and the experimental group (those who participated in the antianxiety program) recorded their anxiety levels several times each day. Joann was unaware that midterm exams also happened to take place during the 1-month time period of her experiment. Joann's experiment is now confounded by: a. a maturation effect b. a history effect c. regression to the mean d. a mortality effect

b. a history effect

11. Most psychology experiments suffer from the __________ problem because of the type of subjects used. a. diffusion of the treatment problem b. college sophomore problem c. regression to the mean problem d. mortality problem

b. college sophomore problem

9. If you were to use a bathroom scale to weigh mice in an experimental setting, your experiment would most likely suffer from a: a. ceiling effect b. floor effect c. practice effect d. fatigue effect

b. floor effect

14. If the null hypothesis is false, then the t test should be: a. equal to 0.00 b. greater than 1. c. greater than .05 d. greater than .95

b. greater than 1.

2. In an experimental study of the effects of stress on appetite, stress is the: a. dependent variable b. independent variable c. control group d. experimental group

b. independent variable

15. Imagine that you conducted an independent-groups t test with 10 participants in each group. For a one-tailed test, the tcv at p = 0.05 would be: a. 1.729 b. 2.101 c. 1.734 d. 2.093

c. 1.734

3. In an experimental study of the effects of stress on appetite, subjects are randomly assigned to either the no-stress group or the stress group. These groups represent the __________ and the __________, respectively. a. independent variable; dependent variable b. dependent variable; independent variable c. control group; experiment group d. experiment group; control group

c. control group; experiment group

17. Cohen's d is a measure of __________ for a __________. a. significance; t test b. significance; X^2 test c. effect size; t test d. effect size; X^2 test

c. effect size; t test

4. The extent to which the results of an experiment can be attributed to the manipulation of the independent variable, rather than to some confounding variable refers to: a. external validity b. generalization to populations c. internal validity d. both c and d

c. internal validity

6. Joe scored very low on the SAT the first time he took it. Based on the confound of __________, if Joe were to retake the SAT, his score should __________. a. instrumentation; increase b. instrumentation; decrease c. regression to the mean; increase d. regression to the mean; decrease

c. regression to the mean; increase

16. If a researcher reported for an independent-groups t test that t(26) = 2.90, p < .005, how many subjects were there in the study? a. 13 b. 26 c. 27 d. 28

d. 28

8. Controlling subject effects is to controlling both subject and experimenter effects as __________ is to __________ a. fatigue effects; practice effects b. practice effects; fatigue effects c. double-blind experiment; single-blind experiment d. single-blind experiment; double-blind experiment

d. single-blind experiment; double-blind experiment

7. When the confound of mortality occurs: a. subjects are lost equally from both the experimental and control groups b. subjects die as a result of participating in the experiment c. subjects boycott the experiment d. subjects are lost differentially from the experimental and control groups

d. subjects are lost differentially from the experimental and control groups

10. If we were to conduct a replication in which we increased the number of levels of the independent variable, we would be using a(n) __________ replication. a. exact b. conceptual c. nonexperimental d. systematic

d. systematic replication