66

Surveys come in many varieties in terms of both time—when or with what frequency a survey is administered—and administration—how a survey is delivered to respondents. This section will examine types of surveys that exist in terms of both time and administration.

With regards to time, there are two main types of surveys: cross-sectional and longitudinal. Cross- sectional surveys are those that are administered at just one point in time. These surveys offer researchers a sort of snapshot in time, and give you an idea about how things are for your respondents at the particular point in time that the survey is administered. One problem with cross-sectional surveys is that the events, opinions, behaviours, and other phenomena that such surveys are designed to assess do not generally remain stagnant. Therefore, generalizing from a cross-sectional survey can be tricky; perhaps you can say something about the way things were in the moment that you administered your survey, but it is difficult to know whether things remained that way for long afterwards. Cross-sectional surveys have many important uses; however, researchers must remember what they have captured by administering a cross-sectional survey: a snapshot of life at the time the survey was administered.

One way to overcome this occasional problematic aspect of cross-sectional surveys is to administer a longitudinal survey. Longitudinal surveys enable a researcher to make observations over some extended period of time. There are several types of longitudinal surveys, including trend, panel, and cohort surveys. We will discuss all three types here, along with another type of survey called retrospective. Retrospective surveys fall somewhere in between cross-sectional and longitudinal surveys.

The first type of longitudinal survey is called a trend survey. Researchers conducting trend surveys are interested in how people’s inclinations change over time, i.e., trends. The Gallup opinion polls are an excellent example of trend surveys. You can read more about Gallup on their website: http://www.gallup.com/Home.aspx. To learn about how public opinion changes over time, Gallup administers the same questions to people at different points in time.

The second type of longitudinal study is called a panel survey. Unlike in a trend survey, the same people participate in a panel survey each time it is administered. As you might imagine, panel studies can be difficult and costly. Imagine trying to administer a survey to the same 100 people every year for, 5 years in a row. Keeping track of where people live, when they move, and when they die, takes resources that researchers often do not have. When those resources are available, however, the results can be quite powerful.

Another type of longitudinal survey is a cohort survey. In a cohort survey, a researcher identifies some category of people that are of interest and then regularly surveys people who fall into that category. The same people do not necessarily participate from year to year, but all participants must meet whatever categorical criteria fulfill the researcher’s primary interest. Common cohorts that may be of interest to researchers include: people of particular generations or those who were born around the same time period; graduating classes; people who began work in a given industry at the same time; or perhaps people who have some specific life experience in common.

All three types of longitudinal surveys permit a researcher to make observations over time. This means that if the behaviour or other phenomenon that interests the researcher changes, either because of some world event or because people age, the researcher will be able to capture those changes.

Table 8.1 Three types of longitudinal surveys sample

Finally, retrospective surveys are similar to other longitudinal studies in that they deal with changes over time but, like a cross-sectional study, they are administered only once. In a retrospective survey, participants are asked to report events from the past. By having respondents report past behaviours, beliefs, or experiences, researchers are able to gather longitudinal-like data without actually incurring the time or expense of a longitudinal survey. Of course, this benefit must be weighed against the possibility that people’s recollections of their pasts may be faulty.

When or with what frequency a survey is administered will determine whether your survey is cross-sectional or longitudinal. While longitudinal surveys are certainly preferable in terms of their ability to track changes over time, the time and cost required to administer a longitudinal survey can be prohibitive. As you may have guessed, the issues of time described here are not necessarily unique to survey research. Other methods of data collection can be cross-sectional or longitudinal—these are really issues of research design. We have placed our discussion of these terms here because they are most commonly used by survey researchers to describe the type of survey administered. Another aspect of survey administration deals with how surveys are administered and we will examine that next.