Deck 10: Designing, Conducting, Analyzing, and Interpreting Experiments With Two Groups

Question 1

What kind of statistical analysis was used?

Answer 1

independent samples t test

Question 2

Understanding Experiments with Two Groups - Answer Key
Twenty sets of depressed twins are obtained for a study on the effects of a new antidepressant. In each twin set, one twin is assigned to receive the drug, and the other is designed to receive the placebo. Three months later, depression levels are measured on a scale from 1 (not at all depressed) to 7 (very depressed). The following data was obtained:

What kind of research design was used?

Answer 2

natural pairs

Question 3

Understanding Experiments with Two Groups - Answer Key
Twenty sets of depressed twins are obtained for a study on the effects of a new antidepressant. In each twin set, one twin is assigned to receive the drug, and the other is designed to receive the placebo. Three months later, depression levels are measured on a scale from 1 (not at all depressed) to 7 (very depressed). The following data was obtained:

What kind of statistical analysis was used?

Answer 3

correlated groups t test

Question 4

What is the dependent variable?

Question 5

What kind of research design was used?

Question 6

Is the effect size small, medium, or large? How do you know?

Question 7

Understanding Experiments with Two Groups - Answer Key
Twenty sets of depressed twins are obtained for a study on the effects of a new antidepressant. In each twin set, one twin is assigned to receive the drug, and the other is designed to receive the placebo. Three months later, depression levels are measured on a scale from 1 (not at all depressed) to 7 (very depressed). The following data was obtained:

What is the independent variable?

Question 8

Understanding Experiments with Two Groups - Answer Key
Twenty sets of depressed twins are obtained for a study on the effects of a new antidepressant. In each twin set, one twin is assigned to receive the drug, and the other is designed to receive the placebo. Three months later, depression levels are measured on a scale from 1 (not at all depressed) to 7 (very depressed). The following data was obtained:

What is the scale of measurement for the dependent variable?

Question 9

Why do you think the author chose a repeated measures design rather than an independent groups design?

Question 10

Understanding Experiments with Two Groups - Answer Key
Twenty sets of depressed twins are obtained for a study on the effects of a new antidepressant. In each twin set, one twin is assigned to receive the drug, and the other is designed to receive the placebo. Three months later, depression levels are measured on a scale from 1 (not at all depressed) to 7 (very depressed). The following data was obtained:

What is the dependent variable?

Question 11

What is the independent variable?

Question 12

Is the effect size small, medium, or large? How do you know?

Question 13

Write an APA-format conclusion.

Question 14

What is the scale of measurement for the dependent variable?

Question 15

Was the treatment effective? How do you know? Specifically discuss the results from page 44 in your answer, explaining which findings were significant and which were not.

Question 16

The general plan for selecting participants, assigning them to conditions, controlling extraneous variables, and gathering data is known as the ____________ design.

A) control group
B) repeated measures
C) statistical
D) experimental

Question 17

What are some of the threats to internal validity that exist in this study? (see Chapter 8 in your textbook).

Question 18

Write an APA-format conclusion.

Question 19

The belief that explanations should remain simple until the simple explanations are no longer valid is known as the principle of

A) variability.
B) parsimony.
C) repeated measures.
D) independent samples.

Question 20

What is the most basic experimental design?

A) The one-group design
B) The two-group design
C) The three-group design
D) The 2 x 2 design

Question 21

Elliot conducts a study with one experimental group and one control group. Elliot has _______ independent variable(s) with _______ group(s).

A) zero; two
B) one; two
C) two; zero
D) two; one

Question 22

Random ___________ deals with choosing your research participants, whereas random _________ deals with putting those participants into groups.

A) assignment; selection
B) comparison; assignment
C) selection; assignment
D) selection; comparison

Question 23

Suppose you know that you would like to conduct an experiment with two groups, an experimental group and a control group. What is the next question that you face?

A) Should I use a t test or an ANOVA?
B) Should I have more than one independent variable?
C) Should I do an experiment or a correlational study?
D) Should I use an independent groups design or a correlated groups design?

Question 24

Random assignment works best when

A) there are three or more groups instead of two.
B) the researcher can match participants on some predetermined variable.
C) there are multiple dependent variables.
D) the sample size is large.

Question 25

When each member of the population has an equal chance of being chosen for an experiment, the researcher has used

A) random assignment.
B) random selection.
C) convenience sampling.
D) balancing.

Question 26

The ________ variable is manipulated by the researcher, and the ________ variable is the response or behavior that the researcher measures.

A) extraneous; independent
B) extraneous; dependent
C) independent; dependent
D) dependent; independent

Question 27

In a two-group design, the group of participants that receives the IV is referred to as the ________ group, and the group of participants that does not receive the IV is referred to as the _________ group.

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

Question 28

Frances wishes to study the effects of violent videogames on children's levels of aggression. As children come to the lab for the study, she flips a coin. If it turns up heads, the child plays a violent videogame. If it turns up tails, the child plays a nonviolent videogame. Frances has used the technique of

A) random selection.
B) random assignment.
C) creating matched pairs.
D) correlated assignment.

Question 29

When we randomly assign our participants to groups, we create

A) independent groups.
B) matched pairs.
C) natural pairs.
D) All of the above.

Question 30

Undesired variables that may influence the DV and thus invalidate the experiment are known as _________ variables.

A) independent
B) dependent
C) extraneous
D) parsimonious

Question 31

Jamonn conducts a study in which one group of participants is randomly assigned to be in a 70-degree room, and another group of participants is randomly assigned to be in a 90-degree room. Jamonn will make a

A) within-subjects comparison.
B) matched-subjects comparison.
C) between-subjects comparison.
D) correlated-subjects comparison.

Question 32

Roger conducts an experiment in which some participants receive therapy and others do not. The people who receive therapy are referred to as the _______ group, and the people who do not receive therapy are referred to as the ________ group.

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

Question 33

When we compare groups of participants who were randomly assigned to groups, we are making a

A) within-subjects comparison.
B) between-subjects comparison.
C) correlated-subjects comparison.
D) matched-subjects comparison.

Question 34

The differing amounts of the IV are referred to as

A) within-groups variability.
B) levels.
C) correlations.
D) repeated measures.

Question 35

Which of the following is the most parsimonious experimental design?

A) The one-group design
B) The two-group design
C) The three-group design
D) The 2 x 2 design

Question 36

Suppose you know that you would like to conduct a study with one independent variable. What is the next question that you face?

A) How many groups will my IV have?
B) What type of participant groups do I have?
C) Should I use a t test for independent samples or a t test for correlated samples?
D) Should I use matched pairs, repeated measures, or natural pairs?

Question 37

Why is random assignment important?

A) Random assignment ensures that the groups are matched on some variable before the experiment.
B) Random assignment helps to make the groups equal on a variety of variables.
C) Random assignment ensures that each member of the population has an equal chance of being chosen to be in the experiment.
D) Random assignment increases the test-retest reliability of the experiment.

Question 38

In an experiment, the FEWEST number of independent variables that you can have would be

A) zero.
B) one.
C) two.
D) Cannot determine without more information.

Question 39

A method of assigning research participants to groups so that each participant has an equal chance of being in any group is known as

A) random selection.
B) random assignment.
C) between-subjects assignment.
D) correlated assignment.

Question 40

Bernice conducts a study on the effects of violent television on children. She obtains a sample of 30 aggressive children and 30 non-aggressive children. She has the aggressive children watch 15 minutes of aggressive television and the non-aggressive children watch 15 minutes of non-aggressive television. This study represents a _________ study.

A) correlational
B) confounded
C) within-subjects
D) All of the above.

Question 41

When we compare groups of participants who were assigned to groups through matched pairs, natural pairs, or repeated measures, we are using a

A) between-subjects comparison.
B) random assignment comparison.
C) within-subjects comparison.
D) control-subjects comparison.

Question 42

Research participants in a two-group design who are measured and equated on some variable before the experiment are referred to as

A) repeated measures pairs.
B) matched pairs.
C) natural pairs.
D) between-subjects pairs.

Question 43

When we test participants more than once, we are using a

A) repeated measures design.
B) between-subjects design.
C) matched pairs design.
D) natural pairs design.

Question 44

Julie measures participants' anxiety levels before treatment and again after treatment. Julie is using a ____________ design.

A) between-subjects
B) natural pairs
C) matched pairs
D) repeated measures

Question 45

Which of the following is NOT a practical consideration for repeated measures designs?

A) Can we measure our DV more than once?
B) Can our participants cope with repeated testing?
C) Can we remove the effects of the IV?
D) Can we use more than one IV?

Question 46

Which of the following considerations is MOST important when using matched pairs?

A) The researcher should make sure to use biologically related participants to create matched pairs.
B) The researcher should make sure to have a large enough sample size to increase the chances that random assignment will be successful.
C) The researcher should make sure to match on a variable that will affect the dependent variable.
D) All of the above are important considerations for matched pairs.

Question 47

Beth is interested in studying the effects of movies on peoples' attitudes toward the mentally ill. She obtains a sample of college students who have never seen One Flew Over the Cuckoo's Nest. Half of the students watch the movie and half do not, and then she measures their attitudes toward the mentally ill. She is worried that if participants have a loved one who is mentally ill, they may have different attitudes from everyone else. She decides to give a pretest to determine if people have family members with a mental illness to make sure that there are equal numbers of such people in both the experimental and control groups. Beth is using

A) repeated measures.
B) random assignment.
C) natural pairs.
D) matched pairs.

Question 48

Research participants in a two-group design who are naturally related in some way (e.g., twins) are referred to as

A) matched pairs.
B) repeated measures pairs.
C) between subjects pairs.
D) natural pairs.

Question 49

Which of the following is an advantage of correlated-groups designs?

A) Correlated-groups designs help to control participant (subject) variables.
B) Correlated-groups designs are better than independent-groups designs when the researcher cannot remove the effects of the IV.
C) Correlated-groups designs use random assignment and independent-groups designs do not.
D) All of the above are advantages of correlated-groups designs.

Question 50

In a ___________ design, participants serve as their own controls.

A) between-subjects
B) natural pairs
C) repeated measures
D) matched pairs

Question 51

Burkley et al. (2000) conducted a study in which half of the consent forms had a "right to withdraw" statement and the other half didn't. What kind of design would NOT be appropriate for this study?

A) matched pairs design.
B) between-subjects design.
C) natural pairs design.
D) repeated measures design.

Question 52

Certain dependent variables, such as solving puzzles and completing mazes, are difficult to administer more than once. For these research projects, researchers typically avoid which kind of design?

A) matched pairs
B) repeated measures
C) between-subjects
D) natural pairs

Question 53

If you only have a small number of participants available, you should use which type of assignment to groups?

A) random assignment
B) correlated assignment
C) independent assignment
D) Both (a) and (c) are correct.

Question 54

When researchers cannot remove the effect of an IV, they are NOT likely to choose which type of research design?

A) repeated measures
B) matched pairs
C) between-subjects
D) natural pairs

Question 55

Random assignment controls ________ extraneous variables.

A) known
B) unknown
C) correlated-groups
D) ex post facto

Question 56

We use _________ assignment whenever there is a relationship between the participants in the groups.

A) random
B) correlated
C) confounded
D) experimental

Question 57

A researcher has pairs of rat littermates and always assigns one littermate to the experimental group and one littermate to the control group. This researcher is using

A) matched pairs.
B) natural pairs.
C) repeated measures pairs.
D) between subjects pairs.

Question 58

Which of the following is NOT associated with a within-subjects comparison?

A) Natural pairs
B) Matched pairs
C) Repeated measures
D) Random assignment

Question 59

With ________ assignment, we equate groups on a specific variable, and with _______ assignment, we leave the equating process to chance.

A) matched; random
B) statistical; matched
C) random; matched
D) matched; statistical

Question 60

Which of the following is NOT a way to use correlated assignment?

A) Random selection
B) Matched pairs
C) Repeated measures
D) Natural pairs

Question 61

What are the two primary advantages of correlated-groups designs?

A) control issues and statistical issues
B) random assignment and control issues
C) random assignment and statistical issues
D) control issues and heterogeneity of variance issues

Question 62

Which of the following represents the general formula for statistical tests?

A) error variability / between-groups variability
B) within-groups variability / error variability
C) error variability / within-groups variability
D) between-groups variability / error variability

Question 63

Independent variables can

A) contrast the presence versus the absence of some variable.
B) contrast "high" versus "low" amounts of some variable.
C) be measured rather than manipulated in an ex post facto design.
D) All of the above.

Question 64

Why does using a correlated-groups design reduce error variability?

A) The independent variable is stronger in a correlated-groups design than in a between-subjects design.
B) The dependent variable is stronger in a correlated-groups design than in a between-subjects design.
C) The correlated-groups design is better suited to multiple independent variables compared to the between-subjects design.
D) Error variability due to individual differences in participants is decreased in a correlated-groups design.

Question 65

Which of the following is an advantage of independent-groups designs?

A) Independent-groups designs have reduced error variability compared to correlated-groups designs.
B) Independent-groups designs have more statistical power than correlated-groups designs.
C) Independent-groups designs have fewer degrees of freedom than correlated-groups designs.
D) Independent-groups designs are easier to plan and execute than correlated-groups designs.

Question 66

Variability in DV scores that is due to the effects of the IV is known as __________ variability.

A) between-groups
B) error
C) within-subjects
D) degrees of freedom

Question 67

In an experiment that involves two groups, there is/are _____ source(s) of variability.

A) No
B) 1
C) 2
D) 3

Question 68

In a correlated-groups design, error variability due to individual differences _________, which makes it ________ to find a significant effect.

A) increases; harder
B) increases; easier
C) decreases; harder
D) decreases; easier

Question 69

An experiment in which the experimenter directly manipulates the IV is known as a(n)

A) ex post facto research design.
B) participant observation.
C) correlational research design.
D) true experiment.

Question 70

When the number of observations in each group is equal, the critical t value in a correlated groups design is ________ the critical t value in an independent-groups design.

A) the same as
B) larger than
C) smaller than
D) always three points greater than

Question 71

A research approach in which the experimenter cannot directly manipulate the IV but can only measure an IV because it is predetermined is known as a(n)

A) case study.
B) true experiment.
C) ex post facto research design.
D) participant observation.

Question 72

In a _______ design, we generally have greater certainty regarding the equality of the groups before the experiment begins than with a _______ design.

A) between-subjects; correlated groups
B) positively correlated; negatively correlated
C) negatively correlated; positively correlated
D) correlated-groups; between-subjects

Question 73

Suppose you conducted an experiment with 20 participants in each group. You would have _____ degrees of freedom in an independent-groups design and _____ degrees of freedom in a correlated-groups design.

A) 38; 19
B) 19; 38
C) 20; 20
D) 18; 19

Question 74

Which of the following is a similarity between the two independent-groups design and the two correlated-groups design?

A) Both designs involve two independent variables.
B) Both designs involve the same kind of assignment to groups.
C) Both designs involve one independent variable with two groups.
D) Both designs involve a correlational design rather than an experimental design.

Question 75

The goal in an experiment is to __________ the between-groups variability and ___________ the error variability.

A) maximize; maximize
B) minimize; minimize
C) maximize; minimize
D) minimize; maximize

Question 76

A correlated-groups design reduces error variability by reducing error due to

A) measurement errors.
B) extraneous variation.
C) individual differences.
D) All of the above.

Question 77

________ statistical values are associated with significant differences in your experiment.

A) Extra-small
B) Small
C) Medium
D) Large

Question 78

Variability in DV scores that is due to factors other than the IV is known as _________ variability.

A) degrees of freedom
B) between-groups
C) error
D) within-subjects

Question 79

Degrees of freedom in the two-correlated groups design are _______, and degrees of freedom in the two-independent groups design are _________.

A) N - 1; N - 1
B) N - 2; N - 2
C) N - 1; N - 2
D) N - 2; N - 1

Question 80

Error variability consists of

A) individual differences.
B) measurement errors.
C) extraneous variation.
D) All of the above.