03_External Validity (Generalizability)

Question 1

External Validity

Answer 1

The external validity of a study is determined by the extent to which the outcomes are generalizable.

In general, study outcomes are generalizable if they can be extended beyond the sample.

Question 2

The external validity of a study with a sample comprised of all males is not flawed unless ___

Answer 2

the researchers claim that the findings are generalizable to females.

Question 3

Examine how two different teaching methods for research methods course affect final exam score

Answer 3

IV = teaching method
• Treatment Group (n=50)
• Control Group (n=50)
• Random assignment to group
DV = final exam score

Treatment
● 7.5weeks(lengthof course)
● Two, 2-hour lectures per week
● One,1-hour discussion session per week

Control
● 7.5weeks(lengthof course)
● Two, 2-hour lectures per week

Findings: Treatment group outperformed control group on mean final exam scores by 6.3%

Question 4

Generalizability Questions

Answer 4

• Can the findings be applied to other participants in the same population, or to other populations?
• Do findings generalize to all 500 graduate psychology students?
• Do findings generalize to 2000 psychology undergraduates?
• Do findings generalize to all 6000 graduate students?

Question 5

Can the findings be applied to other times?

Answer 5

• Do the findings generalize to psychology graduate students 5 years from now? 10 years from now?

Question 6

questions for Beyond the Sample

Answer 6

Can the findings be applied to other researchers?
• Do findings generalize to study by economic professors?
Can the findings be applied to other treatments?
• Do the findings generalize to a study in which learning time was equal for both treatment and control groups?

experiment (?)= low external validity
Can the findings be applied to other times?
• Do the findings generalize to psychology graduate students 5 years from now? 10 years from now?

Can the findings be applied to other researchers?
• Do findings generalize to study by economic professors?
Can the findings be applied to other treatments?
• Do the findings generalize to a study in which learning time was equal for both treatment and control groups?

Question 7

External & Internal Validity

Answer 7

Two views of the relationship between external and internal validity:

1. Trade-off: Higher internal validity leads to lower external validity
2. Prerequisite: There is no external validity without internal validity.

(external for generalization w.)

Question 8

A Note on Qualitative Research

Answer 8

Generalizability is not an expectation of qualitative research.
• Transferability = “Thick Description”
• Systematicity and Transparency

• A lack of generalizability is NOT a flaw of qualitative research.
Qualitative Research - specific orientation

Question 9

No study can be completely ____?

Answer 9

externally valid!

Question 10

Replication is the ultimate ___

Answer 10

test of external validity