Tests, Scales, Populations, Reliability, and Validity, Coursework Example

The validity and reliability of a study is reliant on numerous factors, specifically the population, the scale of measurement and type of the test. There are also a wide range of variables that can come into play to adversely affect the study, or interfere with the validity of results. Shifts in the population can have a significant effect on study validity as well, and make the study group unreliable (Frankfort-Nachmias & Nachmias, 2008).

In the Article “Walk Texas” Self-efficacy was measured on a 3-point scale where responses ranged from unsure (0) to sure (2). Responses were scaled on an overall self-efficacy score ranging from 0 to 20. “The items were scored on a 3-point Likert-typed scale from never (1) to always (3). The coefficient alpha for these items was a = .63 in this study (Bartholomew, Miller, Ciccolo, Atwood & Gottlieb, 2008).” Perceived barriers were measured using a seven-item scale. The “Walk Texas” population was a study group of 433 women Spanish speaking Hispanic women with a low education level.

According to ‘Walk Texas,” population has a complex effect on the validity of study. The authors note that “Our sample size was lowered due to transfer and drop-out of study participants. Although the respondents and non-respondents did not differ on the outcome variables at baseline, the representativeness of our sample is limited (Bartholomew, Miller, Ciccolo, Atwood & Gottlieb, 2008).” The authors also noted that scheduling of certification and education visits were not all controlled. This made the ability to have multiple follow-up points impossible.

One key measure to put in place to insure that scale and test examples are reliable and valid for another population is to account for any set of populations through keeping the population achievable and at sustainable levels for the validity of the study. In the “Walk Texas” study, the study group was made up of Hispanic Spanish speaking women.  The group was so large that when the certain candidates dropped out, the studies validity was still virtually kept intact. In the case of a different type of study where a more diverse group is required, it could be difficult to gather all the members, and even more difficult to gather a large testing pool.

Work Cited

Bartholomew, J. B., Miller, B. M., Ciccolo, J. T., Atwood, R., & Gottlieb, N. H. (2008). Walk texas! 5-a-day intervention for women, infant, and children (wic) clients: A quasi-experimental study. Journal Community Health, 33, 297-303.

Frankfort-Nachmias, C., & Nachmias, D. (2008).  Research methods in the social sciences (7th ed.). New York: Worth