PSY 121 Chapter Notes - Chapter 9: Nonprobability Sampling, Electrodermal Activity, Behavioral Neuroscience
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The participants or subjects must somehow be selected. The method used to select participants can have a profound impact on external validity. Remember that external validity is defined as the extent to which results from a study can be generalized to other populations and settings. Samples may be drawn from the population using probability sampling or nonprobability sampling techniques. When it is important to accurately describe the population, you must use probability sampling. This is why probability sampling is so crucial when conducting scientific polls. Much research, on the other hand, is more interested in testing hypotheses about behavior: attempting to detect whether x causes y rather than describing a population. Here, the two focuses of the study are the relationships between the variables being studied and tests of predictions derived from theories of behavior. In such cases, the participants may be found in the easiest way possible using nonprobability sampling methods, also known as haphazard or convenience methods.
