DEFINING A POPULATION

When you conduct a study, you want your conclusions to be far-reaching. If you are a psychology student, you may want your results to apply to all laboratory rats, not just the ones in your lab. Similarly, if you are doing a market research survey on whether people in Los Angeles would buy disposable umbrellas, you may want to draw conclusions about everybody in the city. If you are an engineer and you are involved in the development of a particular product, you want to know what kind of a base or population the product is for. The people or objects about whom you want to draw conclusions are called a population .

One of the early steps in any study is nailing down exactly what you want your population to be. The more definite you are in defining populations, the better your understanding of samples and the results of your study will be.

Defining a population may seem straightforward, but often it is not. Suppose that you are a company personnel manager, and you want to study why people miss work. You probably want to draw conclusions only about employees in your particular company. Your population is well defined. However, if you are a graduate student writing a dissertation about the same topic, you face a much more complicated problem. Do you want to draw conclusions about professionals, laborers, or clerical staff? About men or women? Which part of the world is of interest ” a city, a country, or the world as a whole? No doubt, you (and your advisor) would be delighted if you could come up with an explanation for absenteeism that would apply to all sorts of workers in all sorts of places. You are not likely to come up with that kind of explanation, though. Even if you do, you are not likely to come up with the evidence to support it.

All kinds of people miss work because they are sick, but unlike others, the president of Major Corporation probably does not need to stay home waiting for a phone to be installed. The afternoons he takes off to play golf with his buddies are probably not recorded by the personnel office as absenteeism, either. People miss work for lots of reasons, and the reasons are quite different for different kinds of employees. Be realistic and study only a part of the labor force. Absenteeism among laborers in auto factories in Detroit, for example, is a problem with a well-defined population about which you would have a fighting chance to draw some interesting conclusions.