Saylor URL: http://www.saylor.org/books Saylor.org
Step 4: Specify the Sample
Once you have created your questionnaire or other marketing study, how do you figure out who should
participate in it? Obviously, you can’t survey or observe all potential buyers in the marketplace. Instead,
you must choose a sample. A sample is a subset of potential buyers that are representative of
your entire target market, or population being studied. Sometimes market researchers refer to the
population as the universe to reflect the fact that it includes the entire target market, whether it consists
of a million people, a hundred thousand, a few hundred, or a dozen. “All unmarried people over the age of
eighteen who purchased Dirt Devil steam cleaners in the United States during 2009” is an example of a
population that has been defined.
Obviously, the population has to be defined correctly. Otherwise, you will be studying the wrong group of
people. Not defining the population correctly can result in flawed research, or sampling error.
A sampling error is any type of marketing research mistake that results because a sample was utilized.
One criticism of Internet surveys is that the people who take these surveys don’t really represent the
overall population. On average, Internet survey takers tend to be more educated and tech savvy.
Consequently, if they solely constitute your population, even if you screen them for certain criteria, the
data you collect could end up being skewed.
The next step is to put together the sampling frame, which is the list from which the sample is drawn.
The sampling frame can be put together using a directory, customer list, or membership roster. [10] Keep in
mind that the sampling frame won’t perfectly match the population. Some people will be included on the
list who shouldn’t be. Other people who should be included will be inadvertently omitted. It’s no different
than if you were to conduct a survey of, say, 25 percent of your friends, using friends’ names you have in
your mobile phone. Most of your friends’ names are likely to be programmed into your phone, but not all
of them. As a result, a certain degree of sampling error always occurs.
There are two main categories of samples in terms of how they are drawn: probability samples and
nonprobability samples. A probability sample is one in which each would-be participant has a known