Sampling, Special Population

Obtaining a Sample of a Special Population

The concept of obtaining a sample is the same whether the researcher wants to sample the general population or a special population. In either case, the researcher has to determine the sample size and sampling technique that will create a sample that best represents the population (general or special). The main difference is that sampling a special population is more difficult and requires more planning than sampling the general population.

When a researcher has a special population in mind, he or she must determine how to access this population. If a researcher wants to obtain a sample of the general population, there are many options. For example, the researcher could simply call every third number in the phone book, or hand a flyer out to every third house. These methods, however, would take too long and be too expensive for a researcher trying to obtain a sample of a special population. For example, if a researcher needed 100 participants from the general population, using the third-house technique, he or she would need to go to approximately 33 houses. On the other hand, if a researcher is seeking a sample of adults who smoke, he or she could go to every third house but there is no guarantee that an adult from the special population lives at that house. The odds are the researcher would have to go to many more houses to find 33 houses with an adult who smokes, thus costing the researcher time and money.

The most time- and cost-effective way to obtain a sample of a special population is to find a list of people that belong to the special population. For instance, if a researcher wants to study the satisfaction of people who live in a particular neighborhood, it may be possible to find a list of these people through the neighborhood’s homeowners association. If the researcher wants to study professors at a particular university, he or she may be able to use a departmental directory on the university’s website.

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