I’m glad you have the essay written. You can take my ideas and add them into your essay. Here are a few additional sources to cite:

Johnson, P. (1959). Modern sampling methods; theory, experimentation, application. Minneapolis: University of Minnesota Press.

Thompson, S. (2002). Sampling (Wiley Series in Probability and Statistics). New Jersey: Wiley-Interscience.

Weiss, N. (2007). Introductory Statistics (8th Edition). Chicago: Addison Wesley.

Below are my comments.

Task:

Write a brief essay (suggested length of 2 pages) in which you:

A. Explain why random samples are preferred to nonrandom samples.

B. Describe the method of each of the following commonly used sampling techniques:

• Simple random sampling -- This is just selecting a sample at random.

• Stratified sampling -- This is dividing the population up into logical segments and then doing random sampling in each subgroup (strata)

• Single-stage cluster sampling -- This is choosing all of your clusters at the same time and then doing random sampling for each one.

• Multi-stage sampling -- This one chooses the clusters in stages. i.e., choose cities by clustering, then choose neighborhoods by clustering from those cities, then do a random sample from each neighborhood selected.

C. Describe one advantage of each of the following commonly used sampling techniques:

• Simple random sampling -- it’s the best. If you can do it this way and still get what you need it makes analysis the most accurate and interpretable.

• Stratified sampling -- this allows for you to get good representations from each group of interest in your population

• Single-stage cluster sampling -- this allows you to sample from large and disperse areas in an inexpensive way, by taking a larger sample from a few areas rather than a many individual observations across a large area.

• Multi-stage sampling -- This technique allows researchers to sample when it’s too expensive or infeasible to use all elements contained within the initial set of clusters.

D. Describe one limitation of each of the following commonly used sampling techniques:

• Simple random sampling -- For small samples, this approach may leave out members of minority groups.

• Stratified sampling -- Relies on the researchers proportions for each strata. For instance, if the researcher chooses 30% blacks, but there are only 20% blacks in the sample, then they will be overrepresented in the analysis.

• Single-stage cluster sampling -- Makes analysis difficult. It also depends on the (probably false) assumption that a sample from one small area is representative of the population across a larger area.

• Multi-stage sampling -- Makes analysis exceeding difficult since a random sample of observations from a cluster sample are used. It decreases precision and confidence and power in the final analysis.

E. If you choose to use outside sources, include all in-text citations and references in APA format.

----I’ve written the essay but got most of my information from one source. The instructor believes I’ve just copied all the info from the book. When in reality I read the material then interpreted it in my own words. Guess that’s not what he’s looking for. If you could help shed some more light on these subjects and maybe a few sources I could cite… I’d really appreciate it… this is also the 3rd time I’ve turned in this assignment… Guess 3 is my lucky number huh.. Thanks again Greg