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.

1. A stratified sample of 75 doctors, 75 lawyers and 75 engineers who belong to a professional organization in that you belong to.
2. A simple random sample of 150 subscribers to your local newspaper.
3. 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:

• ANOVA (fixed effects, omnibus, one-way)
• small effect size
• alpha =.05
• beta = .2
• 3 groups
• 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 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 five (5) scholarly sources.