A sample is a finite part of a population whose properties are studied to gain information about the whole. When dealing with people, researchers define a sample as a set of respondents (people) selected from a larger population for the purpose of a survey. The difficulty in using sampling lies in planning: a sample's generalizability must be evaluated and a sampling method must be chosen that will best suit the research needs in question.

Sampling methods are divided into two broad categories: probability and nonprobability. The difference between probability and nonprobability sampling is the selection technique employed. Probability sampling includes any method of sampling that utilizes some form of random selection. In order to have a random selection method within probability sampling, you must set up some process or procedure that assures that the different units in your population have equal probabilities of being chosen. Nonprobability sampling, then, does not involve random selection, so researchers cannot know ahead of time the probability of an element being chosen. Though you might be tempted to conclude that nonprobability samples cannot be representative of a population, this is not necessarily the case. When designing a sample or evaluating research that has used sampling, it is important to know the strengths and weaknesses of different types of sampling methods. The more a researcher or consumer of research knows about sampling methods, the better chance he or she has of making smart research decisions.

For this Discussion, select one type of probability sampling and one type of nonprobability sampling and think of potential strengths and weaknesses of each. Then consider ethical considerations that might arise when selecting a sampling method and how you might address them.

Posta description of the types of probability and nonprobability sampling you selected. Then describe two strengths and two weaknesses of each type of sampling. Finally, identify two ethical considerations that may factor into selecting a sampling method and explain how you might address these considerations.