Week 3 – Assignment: Evaluate Sampling Method and Sample Size

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This assignment consists of three parts:

(1) Recommend the steps that should be taken to draw the particular
sample described below. In addition, critically analyze the sampling plan.

A stratified sample of 75 doctors, 75 lawyers, and 75 engineers who
belong to a professional organization that you belong to.
A simple random sample of 150 subscribers to your local newspaper.
A systematic sample of 250 from a subscriber list of a trade publication.
(2) Download the G*Power software provided, and then use the software to
submit the following:
a. Calculate the sample size needed when given these factors:

one-tailed t-test with two independent groups of equal size
small effect size (see Piasta, S.B., & Justice, L.M., 2010)
alpha =.05
beta = .2
Assume that the result is a sample size beyond what you can obtain. Use
the compromise function to compute alpha and beta for a sample half the
size. Indicate the resulting alpha and beta. Analyze the result and
decide if the study should be conducted with a smaller sample size.
Explain your rationale. If the study is not worth doing with the smaller
sample, discuss possible tradeoffs that may make the sample size
feasible for your study.
b. Calculate the sample size needed when given these factors:

small effect size
alpha =.05
beta = .2
3 groups

Week 3 – Assignment: Evaluate Sampling Method and Sample Size

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Assume that ANOVA (fixed effects, omnibus, one-way)
the result is a sample size beyond what you can obtain. Use the
compromise function to compute alpha and beta for a sample approximately
half the size. Give your rationale for your selected beta/alpha ratio.
Indicate the resulting alpha and beta. Give an argument that your study
is worth doing with the smaller sample.

(3) Describe the sampling method that would be appropriate for your
intended research. Be sure to include the specification of the
population, what would be used as a sampling frame, the method, and the
procedure that you would use to draw the actual sample.

Length: Your paper should be between 7-12 pages not including title and
reference page. Feel free to include the results of the G* power
analysis that will add length to the paper.

References: Include a minimum of six (6) scholarly sources.

Other source:
1. Acheson, A. (2010). Sample size. In N. J. Salkind (Ed.), Encyclopedia
of research design (pp. 1300-1301). Thousand Oaks, CA: SAGE
Publications, Inc.
2. Encyclopedia of research design, Salkind (2010)
3. http://www.psychologie.hhu.de/arbeitsgruppen/allgemeine-psychologie-und-arbeitspsychologie/gpower.html

Week 3 – Assignment: Evaluate Sampling Method and Sample Size

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