Introduction to Sampling:Understanding what sampling is and how to properly select a sample for your proposed research study is the backbone of understanding research methods. Researchers use a sample of the population on which to conduct their research and then are able to make valid generalizations about the entire population. By being able to explain why and how they chose their samples, researchers can justifiably state how the results of their research can be applied to the larger population. Defining a sample is not quite as easy as it may appear. Researchers have to determine how to prepare a sample, which includes defining the sample component and the population, evaluating the generalizeablity of the sample, and assessing the diversity of the sample. Next, they have to determine what sampling methods to use and decide between probability samples and non-probability samples. Understanding the concept of sampling is one of the most important aspects of mastering research methods. It is one of the MOST important chapters in this book and this course. No doubt, you will come across the concept of sampling again and again throughout your academic career and your life.
QUESTIONS FOR SAMPLING ASSIGNMENT1. When (if ever) is it reasonable to assume that a sample is not needed because “everyone is the same” – that is, the population is homogeneous? Does this apply to research such as Stanley Milgram’s on obedience to authority? What about investigations of student substance abuse? How about investigations of how people (or their bodies) react to alcohol? What about research on the likelihood of voting?
2. Using the NY Times AND one other newspaper (Choose from the Wilmington News Journal , your local hometown newspaper, OR USA Today) as the other, find one or more newspaper articles reporting the results of an opinion poll. What information does the article provide on the sample that was selected? What additional information do you need to determine whether the sample was a representative one?
3. Using an article from your article collection, find one article that discusses the sample chosen for research. Describe how and why the sample was chosen, and anything else the researchers explained about issues related to sampling for their research project.
4. What are the advantages and disadvantages of probability-based sampling designs compared with non-probability-based designs? Could any of the research described in this chapter with a non-probability based design have been conducted instead with a probability based design? What difficulties might have been encountered in an attempt to use random selection? How would you discuss the degree of confidence you can place in the results obtained from research using a non-probability-based sampling design?
5. Using your own research question, answer the following:
a. Define the sample components and its populationb. What is the diversity of your sample population? How do you know this?c. What kind of sampling method would you use? Why?
6. There are 150 people who belong to your church. The new minister wants to change from using traditional church music to rock-a-billy (a form of pop that combines elements of country and rock music). The Church Elders are not persuaded this change would be welcomes by most parishioners. It is decided that 10% (15 people) will be surveyed. Describe how you would select the group of people to be included in the sample. (In your answer include the following terms: population, population parameter, sampling frame, sampling unites, sample, sample statistics).
7. Using a research article from one of the articles you have read for your class project, explain how the researchers decided on their sample.
8. Identify 2 major reasons why psychology research typically does not involve probability samples.
9. What increases sampling error in probability-based sampling designs? Stratified rather than simple random sampling? Disproportionate (rather than proportionate) stratified random sampling? Stratified rather than cluster random sampling? Why do researchers select disproportionate (rather than proportionate) stratified random samples? Why do they select cluster rather than simple random samples?
10. What are the advantages and disadvantages of probability-based sampling designs compared with nonprobability-based designs?