Question

Dr. Paddock is a counseling psychologist who is interested in decreasing adjustment issues in first-year college students. She is curious if having students create collages of their first few weeks of school and then mailing them home will help students feel they have integrated their new life with their old and, as a result, will help them feel less homesick. She samples a group of 100 incoming college freshmen at her university and measures how homesick they are during the first week of school. During Week 4 of school, she has them make the collage and send it home. During Week 7 of school, she measures their homesickness again. She notices a significant reduction in the amount of homesickness from the pretest to the posttest and concludes that her treatment is effective.

Name two threats to internal validity that are likely to be present in Dr. Paddock’s study, given her particular design. What other explanation do these threats provide for the results found by Dr. Paddock?

Answer 1

Name two threats to internal validity that are likely to be present in Dr. Paddock’s study, given her particular design. What other explanation do these threats provide for the results found by Dr. Paddock?

Two threats that may affect the validity of the experiment are:

- history: where the events that are external to the environment of the experiment will also be affecting the results of the study. Here, there may be events such as making friends or adaptations, that might also result in reduced home sickness, which is not being considered.

- repeated testing: since the participants are being tested for the second time, there is a huge chance that they may remember the correct answers and may answer accordingly. This results in the gain of scores in testing and thus, an increase in scores.

The increase in scores is due to the repeated testing of the same individuals as well as the sheer ignorance of the fact that there may be the environment as well as the residing individuals along with the participants, with the area they are living in and the environment they spending their day, with the frequency of contact with the parents, that might result in the decrease in homesickness, as felt in the first week of intake. Also, Dr.paddock was sure that these tests are going to reduce the homesickness of the students and did not leave any possibilities of any other results even before the commencement of the tests.