Test Construction using
Factor Analysis

Imagine that you have been asked to construct a personality test. You would complete the following steps:

  1. Using your clinical knowledge, logic, and common sense, you would come up with 100ís of questions that you believe relate to personality.
  2. You would then administer your test to as many subjects as possible.
  3. You would enter the responses into a computer in order to do a factor analysis. This technique correlates every item on your test with every other item on your test. The result is a set of "factors" or clusters of items that seem to be intercorrelated.
  4. You would then look at the individual questions in each "factor" and attempt to name them.

Here is an example of a test that only consists of 15 questions.

Subjects are asked to answer True of False to each question.

  1. I consider myself to be a very organized person.
  2. As a person, I possess many positive qualities
  3. I would rather spend time alone reading a good book or watching a movie than going out with a group of people.
  4. Sometimes I feel that no one really likes me.
  5. I prefer coffee to tea.
  6. In any job, meeting deadlines is extremely important.
  7. I believe that most people would like me if they got to know me.
  8. My motto is "the more the merrier!"
  9. I enjoy attending parties.
  10. I often start new projects, but then lose interest and never finish them.
  11. People are always talking about me behind my back
  12. I would prefer to live in a small town rather than a big city.
  13. Many people waste too much of their lives worrying about "crossing their Tís and dotting their Iís".
  14. I would enjoy being a librarian.
  15. I keep a very detailed day planner so I always know what I need to do each day.

When you enter all responses from your entire sample, and conduct a factor analysis, three factors appear.

FACTOR I                              FACTOR II                               FACTOR III

   1 T                                          2 T                                           3 T

   6 T                                          4 F                                           8 F

 10 F                                          7 T                                           9 F

 13 F                                                                                        12 T

 15 T

5. Now it your job to provide descriptors for these factors.




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