CHAPTER 9: Internal Validity by G2iv1V

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									Chapter 9: Internal Validity
Activity 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 Validity
1. A researcher wishes to compare                  a. Maturation
   changes in achievement motivation of            b. Mortality
   males and females during their high             c. Data collector characteristics
   school years. During her study, she             d. Location
   discovers that more males than females          e. Instrumentation
   failed to complete high school.                 f. Regression

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.
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           a. Subject characteristics
       unconsciously grade the exam papers
       in such a way that some students               b. History
       receive lower scores than they deserve.
                                                      c. Maturation
    2. ______ The taking of a pretest by
       students participating in a research           d. Attitude of subjects
       study allows them to figure out the
       nature of this study.                          e. Mortality

    3. ______ Two existing groups are                 f. Data collector bias
       compared with respect to their scores
       on an achievement test.                        g. Testing

    4. ______ A fire drill occurs during the          h. Instrument decay
       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.
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 wil 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?
   ___________________________________________________________________
   ___________________________________________________________________
   ___________________________________________________________________

								
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