Chapter 8 - Between-Subjects Design

Question 1

What are the two basic research designs used to obtain the groups of scores that are compared in an experiment

Answer 1

Within-subjects Design
Between-subjects Design

Question 2

What is a between-subjects design?

Answer 2

When data is obtained from a different group of participants

Question 3

What is the general goal of a between-subjects experiment?

Answer 3

To determine whether differences exist between two or more treatment condition

Question 4

If a researcher wants to compare two teaching methods (two treatments) to determine whether one is more effective than the other. How many groups of individual would there be?

Answer 4

Two separate groups of individuals would be used, one for each of the two teaching methods.

Question 5

If a between-subjects experiment produces 30 scores in treatment A and 30 scores in treatment B, how many total participants are there?

Answer 5

60 participants

Question 6

What is the main advantage of a between-subjects design?

Answer 6

Each individual score is independent from the other scores so the researcher is confident that relatively clean and uncontaminated by other treatment factors

Question 7

A between-subjects experimental design is often called an…

Answer 7

independent-measures experiment design

Question 8

What is the primary disadvantage of the between-subjects design?

Answer 8

Each score is obtained from a unique individual who has personal characteristics that are different from all of the other participants

Question 9

What is the definition of individual differences?

Answer 9

Differences between participants on variables such as gender, age, personality, and family background that exist at the beginning of an experiment

Question 10

Suppose John, a 21 year-old white male, is assigned to treatment A, where he produces a score of 45, and Mary, a 20 year-old black female, is assigned to treatment B and has a score of 51. The researcher has found a 6-point difference between the two scores. The researcher must determine what caused the difference. Notice that the difference in scores could be caused by the different treatment conditions. However, the difference could also be explained by the
fact that…

Answer 10

John and Mary are different people with different characteristics. Thus, the 6-point difference in scores could be caused by individual differences.

Question 11

What accurately describes the scores in a between-subjects experiment?

Answer 11

Only one score is obtained for each treatment

Question 12

If a between-subjects experiment produces 50 scores in treatment 1 and 50 scores in treatment 2, then how many participants were in the entire experiment?

Answer 12

100 participants

Question 13

What are the two major sources of confounding that exist in a between-subjects design:

Answer 13

1. Confounding from individual differences
2. Confounding from environmental variables – EX. One group may be measured primarily during the morning and another group during the afternoon

Question 14

Any extraneous variable that systematically differentiates the groups is a…

Answer 14

confounding variable

Question 15

A primary concern is to ensure that the different groups are…

Answer 15

as similar as possible

Question 16

In a between-subjects experiment, if the participants in one group have characteristics that are different from the participants in another group, then what is threatened?

Answer 16

Internal validity

Question 17

For a between-subjects experiment, what is a possible threat to internal validity?

Answer 17

Individual differences that exist between treatments

Question 18

What are the three procedures researchers typically use to set up groups for a between-subjects experimental study?

Answer 18

1. Random Assignment (Randomization)
   - a random process is used to assign participants to groups i.e coin toss
2. Matched Groups (Matched Assignment)
   - assigning individuals to groups so that a specific participant variable is balanced
   - Requires 2 steps––identifying the variable that needs to be matched across groups and measuring the matching variable for each participant
3. Holding variables constant
   - Hold the variable constant
   Ex. if the researcher suspects that gender might be a confounding variable than they can eliminate gender as a variable by only using female participants

Question 19

What does not guarantee that a specific participant variable will not become a confounding variable?

Answer 19

Randomizing the variable across treatment

Question 20

What is a limitation of using matching rather than random assignment to form groups in a between-subjects experiment?

Answer 20

Matching requires another measurement procedure.

Question 21

How does holding a variable constant prevent the variable from becoming a confound?

Answer 21

It eliminates the possibility that the variable will be substantially different from one group to another