Chapter 9: Internal ValidityActivity 9.1: Threats to Internal Validity

Activity 9.2: What Type of Threat?

Activity 9.3: Controlling Threats to Internal Validity

Activity 9.1: Threats to Internal Validity

Which threat to internal validity exists in each of the situations listed below?

Column A: Situation Column B: Threat to Internal Validity1. A researcher wishes to compare

changes in achievement motivation of males and females during their high school years. During her study, she discovers that more males than females failed to complete high school.

2. Two groups of students are compared with regard to their attitude toward a career in the military. Two different recruiting officers administer the same attitude scale to each group. The recruiter who administers the scale to the first group is in uniform; the second recruiter is in civilian clothes.

3. Those students who score in the top 2 percent on a biology test have, on average, lower scores the second time they take the test.

4. A researcher wants to measure changes in student attitudes toward their graduate programs at a local university. He finds a questionnaire used by another researcher the previous year that asks most of the questions he wants to ask. To improve it, he changes some of the questions and adds a few more.

5. A researcher observes level of attention in a special program during the month of September and again in May.

6. A researcher interviews two groups of individuals. One group is interviewed in his classroom; the other group, although asked the same questions, is interviewed in the student union.

a. Maturationb. Mortalityc. Data collector characteristicsd. Locatione. Instrumentationf. Regression

Activity 9.2: What Type of Threat?

Match the letter of the appropriate research methodology from Column B with its topic in Column A.

Column A: Examples Column B: Type of Threat

1. ______ The scorers of an examination unconsciously grade the exam papers in such a way that some students receive lower scores than they deserve.

2. ______ The taking of a pretest by students participating in a research study allows them to figure out the nature of this study.

3. ______ Two existing groups are compared with respect to their scores on an achievement test.

4. ______ A fire drill occurs during the taking of a final examination. Several students complain they did not have enough time to complete the exam.

5. ______ Change during an intervention is due to just the passing of time rather than the intervention itself.

6. ______ The way in which students are ask to participate in a study affects how they perform.

a. Subject characteristics

b. History

c. Maturation

d. Attitude of subjects

e. Mortality

f. Data collector bias

g. Testing

h. Instrument decay

Activity 9.3: Controlling Threats to Internal Validity

Suggest a way to control each of the following threats to internal validity.

1. Instrument decay ______________________________________________________

_______________________________________________________________________

2. Subject characteristics __________________________________________________

_______________________________________________________________________

3. Loss of subjects (mortality) ______________________________________________

________________________________________________________________________

4. Data collector characteristics _____________________________________________

________________________________________________________________________

5. Location _____________________________________________________________

________________________________________________________________________

6. Regression ___________________________________________________________

_______________________________________________________________________

7. Implementation _______________________________________________________

________________________________________________________________________

8. Attitude of subjects ____________________________________________________

_______________________________________________________________________

Problem Sheet 9: Internal Validity

1. Place an X after any of the threats listed below that you think might apply to your study:

Subject characteristics______ Instrumentation______ Maturation___________

Mortality______Testing ________ History_________Subject attitude________

Implementation_______ Location________Regression_______Other_________

2. Please describe how you will attempt to control for those threats that you have marked above:

Threat #1: ______________________________________________________________________________________________________________________________________

Threat #2: ______________________________________________________________________________________________________________________________________

Threat #3: ______________________________________________________________________________________________________________________________________

Threat #4: ______________________________________________________________________________________________________________________________________

3. What assurances can you provide (through your design, sampling procedures, etc.) to support the claims that your study findings are valid? In other words how will you convince the reader that the findings or relationships resulting from the study are not due to or explained by something other than what you claim? _________________________________________________________________________________________________________________________________________________________________________________________________________