Deck 9: Experimental Design and Analysis I

Question 1

Changes that occur naturally in the subjects over time could result in the confound of​

A)history.
B)maturation.
C)regression to the mean.
D)diffusion of treatment.

Answer 1

maturation.

Question 2

Alison's bathroom scale will not register a weight of more than 130 pounds. Alison does not realize this, and therefore is unaware that she has put on a few pounds until she begins to notice how tight her clothes are. This illustrates the confound of a _____ effect.​

A)ceiling
B)floor
C)practice
D)fatigue

Answer 2

ceiling

Question 3

Sometimes it is difficult to generalize the results of a study to the population because of the _____ problem.

A)diffusion of treatment
B)college sophomore
C)regression to the mean
D)mortality

Answer 3

college sophomore

Question 4

The best advice for those considering retaking the SAT is that if your score was below average you probably ____ retake the test, and if your score was above average you probably ____ retake the test due to _____.​

A)should; should; mortality
B)should; should not; regression to the mean
C)should not; should; regression to the mean
D)should; should not; mortality

Question 5

Independent variable is to dependent variable as _____ is to _____.

A)measure; manipulate
B)manipulate; measure
C)control group; experimental group
D)experimental group; control group

Question 6

A limitation in the ability to differentiate between scores at the bottom of the scale is a _____ and a limitation in the ability to differentiate between scores at the top of the scale is a _____.

A)practice effect; fatigue effect
B)fatigue effect; practice effect
C)ceiling effect; floor effect
D)floor effect; ceiling effect

Question 7

After participating in an experiment on the effects of alcohol on sociability, Megan could not wait to return to her sorority house to tell all of her sisters about it. In this situation, the researcher should be concerned with the confound of​

A)mortality.
B)regression to the mean.
C)testing.
D)diffusion of treatment.

Question 8

A decline in performance due to repeated testing is a(n) _____ effect and improvement in performance due to repeated testing is a(n) _____ effect.​

A)instrumentation; mortality
B)mortality; instrumentation
C)practice; fatigue
D)fatigue; practice

Question 9

In an experimental study of the effects of exercise on stress, stress is the

A)dependent variable.
B)independent variable.
C)control group.
D)experimental group.

Question 10

To say that an experiment contains a confound means that

A)different subjects are assigned to each group.
B)the dependent variable is measured.
C)the independent variable is manipulated.
D)there is an uncontrolled extraneous variable in the experiment.

Question 11

Single-blind experiments help to control for ____ effects whereas double-blind experiments help to control for _____ effects.​

A)participant; experimenter and participant
B)experimenter and participant; participant
C)fatigue; practice
D)practice; fatigue

Question 12

After grading 20 very poor term papers, Professor Jones was so upset by his students' writing that he became even more conscious of errors in their papers. Professor Jones' change in his grading criteria is similar to the confound of

A)mortality.
B)history.
C)instrumentation.
D)diffusion of treatment.

Question 13

Increasing the number of levels of the independent variable is to _____ replication as changing the type of dependent measure is to _____ replication.​

A)exact; conceptual
B)conceptual; exact
C)systematic; exact
D)systematic; conceptual

Question 14

In an experimental study of the effects of exercise on stress, exercise is the​

A)dependent variable.
B)independent variable.
C)control group.
D)experimental group

Question 15

Internal validity is​

A)the extent to which the results of an experiment can be attributed to the manipulation of the dependent variable, rather than to some confounding variable.
B)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.
C)the extent to which the results of an experiment can be generalized.
D)both b and c.

Question 16

In an experimental study of the effects of exercise on stress, subjects are randomly assigned to either the no exercise group or the exercise group. These groups represent the _____ and the _____, respectively.

A)independent variable; dependent variable​
B)dependent variable; independent variable
C)control group; experimental group
D)experimental group; control group

Question 17

Baseline is to treatment as _____ is to _____.​

A)dependent variable; independent variable
B)independent variable; dependent variable
C)control group; experimental group
D)experimental group; control group

Question 18

John conducted an experiment to test the effectiveness of a smoking cessation program. The experiment took place over a 1-month time period. Participants in the control group and the experimental group (those who participated in the smoking cessation program) recorded the number of cigarettes that they smoked each day. John was unaware that "national stop-smoking week" also happened to take place during the 1-month time period of his experiment. John's experiment is now confounded by​

A)maturation.​
B)history.
C)regression to the mean.
D)mortality.

Question 19

When we can generalize from the sample used in a study to the population of interest, we say that the study has _____ validity.

A)internal​
B)external
C)construct
D)content

Question 20

When subjects are lost differentially from the experimental and control groups, any observed effect may be due to

A)mortality.
B)instrumentation.
C)diffusion of treatment.
D)history.

Question 21

The null hypothesis for a two-tailed independent-groups t test states that

A)H₀: m₁ ¹ m₂.​
B)H₀: m₁ = m₂.
C)H_a: m₁ ¹ m₂.
D)H_a: m₁ = m₂.

Question 22

As sample variance _____, the value of the t test _____.​

A)increases; increases
B)decreases; decreases
C)increases; decreases
D)increases; stays the same

Question 23

The alternative hypothesis for a two-tailed independent-groups t test states that​

A)H₀: m₁ ¹ m₂.
B)H₀: m₁ = m₂.
C)H_a: m₁ ¹ m₂.
D)H_a: m₁ = m₂.

Question 24

Which of the following are aspects of a study that can increase power?​

A)greater differences produced by the independent variable
B)smaller variability of raw scores in each condition
C)increased sample size
D)all of the options are correct

Question 25

Briefly explain the confounds of history and maturation.​

Question 26

An independent-groups t test​

A)compares sample means for two related groups.
B)compares sample means for two unrelated groups.
C)compares standard deviations for two unrelated group.
D)compares sample means for three or more unrelated groups.

Question 27

If an independent-groups t test has seven participants in each group, then the degrees of freedom are​

A) 7.
B)14.
C)6.
D)12.

Question 28

Which of the following is not an assumption of the t test for independent groups?

A)The data are interval or ratio.
B)The underlying distributions are bell-shaped.
C)The observations are independent.
D)There is not homogeneity of variance.

Question 29

In an experimental study of the effects of exercise on stress, subjects are randomly assigned to either the no exercise or the exercise conditions. Identify what type of study this is-between-, within-, or matched-subjects. In addition, identify the independent and dependent variables and the control and experimental groups.​

Question 30

Which of the following t test results has the greatest chance of statistical significance?

A)t(28) = 1.70
B)t(14) = 1.70
C)t(18) = 1.70
D)t(10) = 1.70

Question 31

What is a confound and how is it related to internal validity?​

Question 32

A health magazine recently reported a study in which researchers claimed that iron supplements increased memory and problem-solving abilities in a random sample of college women. All of the women took memory and problem-solving tests at the beginning of the study, then took iron supplements, and then took the same tests again at the end of the study. What is wrong with this design? What confounds could be leading to the results of improved memory and problem-solving skills?​

Question 33

When using an independent-groups t test, the difference between the means is divided by the standard error of the

A)mean.
B)standard deviation.
C)difference between means
D)difference between standard deviations.

Question 34

Imagine that you conducted an independent-groups t test with 12 participants in each group. For a two-tailed test, the t_cv at a = .05 would be​

A)±1.717.
B)±2.074.
C)±1.711.
D)±2.064.

Question 35

What are the advantages and disadvantages in the use of a posttest-only control group design versus a pretest/posttest control group design?​

Question 36

If, after calculating an independent-groups t test you find that it is equal to zero, then​

A)the two sample means differ significantly.
B)the two sample means do not differ significantly.
C)you have done something wrong.
D)the two population means differ significantly.

Question 37

If a researcher reported for an independent-groups t test that t(18) = 2.90, p​

A)18
B)20
C)10
D)9

Question 38

If the null hypothesis is true, then the t test should be close to​

A)0.00.
B)±1.65.
C)±1.96.
D)±3.00.

Question 39

For an independent-groups t test, effect size can be measured using​

A)Cohen's d.​
B)the standard error of the difference between means.
C)the phi coefficient.
D)the c² test for independence.

Question 40

For an independent-groups t test, the value of Cohen's d describes​

A)the size of the treatment effect.
B)the chance of a Type I error.
C)the chance of a Type II error.
D)the overall chance level in the experiment.

Question 41

Differentiate between an exact replication, a systematic replication, and a conceptual replication.

Question 42

A student is interested in whether students who study with others devote at much attention to their studies as do students who study alone. He believes those who study alone devote more attention to their studies. He randomly assigns participants to either group or individual study conditions and has them read and study the same passage of information for the same amount of time. Participants are then all given the same 10-item test on the material. Their scores appear below. Scores on the test represent interval/ratio data and are normally distributed.

a) What statistical test should be used to analyze these data?
b) Identify H₀ and H_a for this study.
c) Conduct the appropriate analysis.
d) Should H₀ be rejected? What should the researcher conclude?
e) If significant, compute the effect size and interpret this.
f) If significant, draw a graph representing the data.
g) Calculate the 95% CI.

Question 43

According to some research, males have better spatial skills than do females; and according to other research, females have better reading skills than males. A student is interested in determining which gender performs better on a word-search puzzle (a puzzle in which words are hidden vertically, horizontally, and diagonally within an array of letters) since this type of puzzle involves both spatial and reading skills. A sample of males and females volunteer to participate and are given 10 minutes to work on a 50-word puzzle. The number of words correctly recognized is recorded for each subject, and the resulting data are as follows:
Conduct the appropriate analysis of these data and determine whether there are any significant differences.
​

Question 44

Briefly explain the confounds of testing and regression to the mean.​

Question 45

A college student is interested in whether there is a difference between male and female students in the amount of time spent working out each week. The student gathers information from a random sample of male and female students on her campus. Amount of time spent working out is normally distributed. The data appear below.​

a) What statistical test should be used to analyze these data?
b) Identify H₀ and H_a for this study.
c) Conduct the appropriate analysis.
d) Should H₀ be rejected? What should the researcher conclude?
e) If significant, compute the effect size and interpret this.
f) If significant, draw a graph representing the data.

Question 46

Briefly explain the confounds of instrumentation and mortality.​

Question 47

Briefly explain the relationship between participant effects, experimenter effects, single-blind experiments, and double-blind experiments.​

Question 48

What is the relationship between external validity and the college sophomore problem?​