PSYC*2360 Chapter 8: Two-Group Design

Question 1

For an experiment to establish causation, what are the three specific criteria it must meet?

Answer 1

• Covariation
• Temporal precedence
• Internal validity

Question 2

What is covariation?

Answer 2

When changes in one variable are associated systematically with changes in another

Question 3

What does it mean to have temporal precedence?

Answer 3

When changes in the suspected cause (IV) occur before changes in the effect (DV)

Question 4

T or F: Correlational designs may help establish temporal precedence, but they can’t establish covariation.

Answer 4

False. May help establish covariation, but can’t establish temporal precedence.

Question 5

What term refers to the degree to which it is possible to rule out other possible causal explanations for an observed relationship between the independent and dependent variables?

Answer 5

Internal validity

Question 6

What are extraneous variables?

Answer 6

Factors other than the intended treatment that might change the outcome variable

Question 7

T or F: To establish causality, extraneous variables need to be eliminated or controlled.

Answer 7

True

Question 8

Why is internal validity required for determining causality?

Answer 8

It must be shown that covariation is only due to the independent variable and not an extraneous variable

Question 9

What is mundane realism?

Answer 9

The degree to which a study parallels everyday situations in the real world

Question 10

What is experimental realism?

Answer 10

The degree to which participants becomes engrossed in a manipulation and are truly influenced by it

Question 11

What is a two-group design also known as?

Answer 11

A simple experiment

Question 12

What is a two-group design?

Answer 12

An experimental design that compares two groups or conditions

Question 13

Which experimental design represents the most basic way to establish cause and effect?

Answer 13

A two-group design

Question 14

In an experimental design, which group or condition gets the key treatment?

Answer 14

The experimental group

Question 15

In an experimental design, which group or condition serves as a comparison for the experimental group?

Answer 15

The control group

Question 16

In an experimental design, what is an all-or-nothing approach?

Answer 16

The experimental group treatment to its fullest extent and the control group receives no treatment

Question 17

What is one drawback to an all-or-nothing approach?

Answer 17

It can lead to several differences between groups and make the exact effect of treatment unclear

Question 18

Which term refers to the ability to keep everything between groups the same, except for the one element being tested?

Answer 18

Experimental control

Question 19

In an experimental design, what is an a-little-more-versus-a-little-less approach?

Answer 19

The experimental group receives a bit more of the treatment and the control group receives a little less

Question 20

Which term refers to a clear and specific prediction of how the independent variable will influence the dependent variable?

Answer 20

Experimental hypothesis

Question 21

What is the assumption that each participant represents a unique and individual data point?

Answer 21

Independence

Question 22

T or F: When people know they are part of a certain group, even if arbitrary, they tend to favour that group over others.

Answer 22

True

Question 23

T or F: Even when people are aware that they are part of a group, they don’t often take cues from other members, and each individual continues to act naturally.

Answer 23

False. As soon as people know they are part of a group, they often take cues from other members in ways that make each individual act less naturally.

Question 24

What is one step that can be taken to ensure independence in an experimental design?

Answer 24

Interactions between participants should be minimized, and they should each be tested individually

Question 25

What is random assignment?

Answer 25

Any method of placing participants in groups that is non-systematic and non-biased

Question 26

Which method of assignment to groups ensures that each participant has an equal chance of being in any group?

Answer 26

Random assignment

Question 27

What is a matched-pair design?

Answer 27

A design in which one creates a set of two participants who are highly similar on a key trait, then randomly assigns individuals in a pair to different groups

Question 28

Which type of experimental design ensures both groups have participants who are similar in the trait important to the study?

Answer 28

A matched-pair design

Question 29

When does a matched-pair design work best?

Answer 29

When there are important characteristics that can be easily measured in a reliable and valid way

Question 30

T or F: Matched-pair designs can sometimes give a false sense of security in terms of controlling for individual differences.

Answer 30

True

Question 31

What are researcher notes used for?

Answer 31

To keep track of anything out of the ordinary that happens during a study

Question 32

What is a manipulation check?

Answer 32

A measure that helps determine whether the manipulation effectively changed or varied the independent variable across conditions

Question 33

What are the three tasks to accomplish during data analysis in a two-group design to help answer the research question?

Answer 33

- Make sure groups were similar on variables that may provide alternative explanations - Make sure manipulation was effective - Test hypothesis

Question 34

In an experiment with a between-subjects design with two levels of the IV and a continuous DV, what is the appropriate statistical analysis to conduct?

Answer 34

A t-test for independent means (aka an independent samples t-test)

Question 35

Which statistical test is used to compare groups' means to see if they differ to a degree that could not have happened accidentally or by chance?

Answer 35

A t-test for independent means (aka an independent samples t-test)

Question 36

How are degrees of freedom calculated in an independent samples t-test?

Answer 36

df= (n1-1)(n2-1)

Question 37

In an independent samples t-test, what does p represent?

Answer 37

The probability that the results were due to chance (statistical significance)

Question 38

In an independent samples t-test, what does it typically mean when p<0.05?

Answer 38

There can be confidence that the results represent a real difference between groups

Question 39

In an independent samples t-test, what does it typically mean when p>0.05?

Answer 39

There is not enough evidence to support that the results were not merely due to chance

Question 40

In an independent samples t-test, as n increases, does p increase or decrease?

Answer 40

Decreases

Question 41

T or F: The statistical significance in a t-test is independent of sample size.

Answer 41

False

Question 42

In an independent samples t-test, what does d represent?

Answer 42

Effect size

Question 43

What is the statistical measure of the magnitude of the difference between groups?

Answer 43

Effect size (d)

Question 44

T or F: The effect size is independent of sample size.

Answer 44

True

Question 45

In an independent samples t-test, are significance level and effect size independent of one another?

Answer 45

Yes

Question 46

Is Cohen's effect size of 0.2 considered small, medium, or large?

Answer 46

Small

Question 47

Is a Cohen's effect size of 0.5 considered small, medium, or large?

Answer 47

Medium

Question 48

Is a Cohen's effect size of 0.8 considered small, medium, or large?

Answer 48

Large

Question 49

What is the null hypothesis?

Answer 49

The hypothesis that there will be no difference between groups or conditions

Question 50

Which hypothesis is the researcher typically trying to statistically reject?

Answer 50

The null hypothesis