Psyc 310 Ch.8

Front 1

What is the goal of the experimental research strategy?

Back 1

To demonstrate a cause and effect relationship between variables

Front 2

What are the four core features of the experimental research strategy?

Back 2

1. Manipulation of one variables

2. Measurement of a second variable

3. Comparison of the scores between treatments

4. Control of all other variables.

Front 3

What are the two basic designs of experimental research strategy?

Back 3

-Within subject designs

-Between subject designs

Front 4

What is a within-subject design?

Back 4

-Different sets of scores are obtained from the same group of participants

Front 5

What is between subjects design?

Back 5

-Each set of scores is obtained from different groups of participants

Front 6

How does an experimenter do a between-subject design in experimental research?

Back 6

A researcher manipulates an independent variables and then measures the dependent variable for each participant.

Front 7

What is the goal of the between-subject design?

Back 7

To determine whether differences exist between two or more treatment conditions.

Front 8

What is a requirement in between-subject designs?

Back 8

Only one score for each participant is obtained.

-Separate groups of participants are used for different treatment conditions.

Front 9

What are the advantages of between subject designs?

Back 9

Each individual score is independent from all other scores ((because each participant is measured only once, the researcher can be reasonably confident that the resulting measurement is relatively clean and uncontaminated by other factors.))

Front 10

In a between-subject design the individual's score is not influenced by which 3 factors?

Back 10

1. Practice or experience gained in other treatments

2. Fatigue or boredom from participating in a series of different treatments

3. Contrast effects that result from comparing one treatment to another.

Front 11

What are the disadvantages to between-subjects designs?

Back 11

1. Requires a large number of participants as one participant contributes only one score.

2. Each score is obtained from a unique individual who has personal characteristics different from all of the other participants. (may produce high variability)

Front 12

What is a confounding variable?

Back 12

Any extraneous variable systematically differentiating the groups.

Front 13

What is an assignment bias?

Back 13

Confounding from individual differences

Ex: participants in one group may be older, smarter, taller or have higher socio-economic status than the participants in another group.

Front 14

What are confounding from environmental variables?

Back 14

Any characteristic of the environment that may differ.

Front 15

What is the purpose of equivalent groups?

Back 15

Protecting a study from assignment bias

Front 16

How would one create an equivalent group in a between-subjects design? The separate groups much be:

Back 16

-Creating equally: the process must be as similar as possible.

-Treated equally: participants should receive exactly the same experiences

-Composed of equivalent individuals: the characteristics of the participants in any one group should be as similar as possible to the characteristics of every other group.

Front 17

How would one limit confounding variables by individual differences in a between-subjects design?

Back 17

1. Random assignment

2. Marching groups (matched assignment): no group is noticeably different from the other.

3. Holding variables constant (by using all females or all males, or similar IQs)

Front 18

What causes variability in between-subject designs?

Back 18

-Large differences between individuals produces a large variance

Front 19

What happens when one increases or decreases variability in a between-subject design?

Back 19

-May have a significant influence on the statistical interpretation of the study results.

Front 20

What does significant imply in terms of influence?

Back 20

It is very unlikely that the difference would occur if there was not a consistent difference between treatment conditions.

Front 21

What is variance?

Back 21

A statistical value that measures the size of the differences from one score to another.

Front 22

Are large differences between treatments good or bad?

Back 22

Good as they provide evidence of differential treatment effects.

Front 23

Are large differences within treatments good or bad?

Back 23

Bad: differences that exist inside the treatment conditions determine the variance of the scores.

(Large variance can hide patterns in the data)

Front 24

Researchers try to _____ differences between treatments.

Back 24

Increase

Front 25

Researcher try to ____ variance within treatments

Back 25

Decrease

Front 26

How would one limit variance within treatments of between-subject designs?

Back 26

-Standardize procedures and treatment settings

-Limit individual differences

-Random assignment and matching

-Sample size

Front 27

Limiting variance within treatment of between-subject designs: how would one limit individual differences?

Back 27

-Create equivalent groups

-Reduce variance within groups

Front 28

Other threats to internal validity between-subjects: Differential attrition (What is it?)

Back 28

Withdrawal from research study before it is completed. Can threaten internal validity.

Front 29

What is diffusion (between subjects)

Back 29

Spread of the treatment effects from the experimental group to the control group, which tends to reduce the difference between the two conditions - threats to internal validity.

Front 30

Threats to internal validity of between-subjects: Communication between groups : Compensatory equalization

Back 30

Subject demands treatment received by the other group.

Front 31

Threats to internal validity of between-subjects: Communication between groups : When does Compensatory rivalry happen?

Back 31

Occurs when participants in an untreated group change their normal behavior when they learn about a special treatment that is given to another group.

Front 32

Threats to internal validity of between-subjects: Communication between groups : When does resentful demoralization happen?

Back 32

Participants in control group become less productive and less motivated "give up"

Front 33

What is a two group design (in between-subject)

Back 33

Comparing only two groups of participants: the researcher manipulates one independent variable with only two levels.

Front 34

When is the two group design used in between-subject experimental study?

Back 34

Can be used to compare treatments, or to evaluate the effect of one treatment by comparing a treatment group and a control group.

Front 35

What is the primary advantage of the two -group design in an in-between subject experimental study?

Back 35

Provides the best opportunity to maximize the difference between the two treatment conditions; oppose extreme values can be selected for the independent variable

Front 36

What is the primary disadvantage of the two -group design in an in-between subject experimental study?

Back 36

Provides little information. researcher obtains only two real data points for comparison. Limits study to only two groups.

Front 37

Comparing means for more than two groups: What is a single factor multiple-group designs?

Back 37

Ex: comparing driving performances under three telephone conditions

Front 38

Comparing proportions for two or more groups: What does the researcher do when he does not have a numerical score?

Back 38

-Each participant is classified into a category

-Data consist of a simple frequency count of the participants in each category on the scale of measurement.

-Data can be analyzed on a chi-square test for independence : compares proportions within groups.