REASONS FOR USING CONVENIENCE SAMPLES

Much of the research in psychology uses nonprobability sampling techniques to obtain participants for either surveys or experiments. The advantage of these techniques is that the investigator can obtain research participants without spending a great deal of money or time on selecting the sample. For example, it is common practice to select participants from students in introductory psychology classes. Often, these students are asked to participate in studies being conducted by faculty and their students; the introductory psychology students can choose which studies they wish to participate in.

Even in studies that do not use college students, the sample is often based on convenience rather than concern for obtaining a random sample. One of our colleagues studies children, but they are almost always from one particular elementary school. You can guess that this is because our colleague has established a good relationship with the teachers and administrators; thus, obtaining permission to conduct the research is fairly easy. Even though the sample is somewhat biased because it includes only children from one neighborhood that has certain social and economic characteristics, the advantages outweigh the sample concerns for the researcher.

Why aren’t researchers more worried about obtaining random samples from the “general population” for their research? Most psychological research is focused on studying the relationships between variables even though the sample may be biased (e.g., the sample will have more college students, be younger, etc., than the general U.S. population). But to put this in perspective, remember that even a random sample of the general population of U.S. residents tells us nothing about citizens of other countries. So, our research findings provide important information even though the data cannot be strictly generalized beyond the population defined by the sample that was used. For example, the findings of Brown and Rahhal (1994) regarding experiences of younger and older adults when they hid an object but later forgot the location Page 156are meaningful even though the actual sample consisted of current students (younger adults) and alumni (older adults) of a particular university who received a mailed questionnaire. In Chapter 14, we will emphasize that generalization in science is dependent upon replicating the results. We do not need better samples of younger and older adults; instead, we should look for replications of the findings using multiple samples and multiple methods. The results of many studies can then be synthesized to gain greater insight into the findings (cf. Albright & Malloy, 2000).

These issues will be explored further in Chapter 14. For now, it is also important to recognize that some nonprobability samples are more representative than others. Introductory psychology students are fairly representative of college students in general, and most college student samples are fairly representative of young adults. There are not many obvious biases, particularly if you are studying basic psychological processes. Other samples might be much less representative of an intended population. Not long ago, a public affairs program on a local public television station asked viewers to dial a telephone number or send email to vote for or against a gun control measure being considered by the legislature; the following evening, the program announced that almost 90% of the respondents opposed the measure. The sampling problems here are obvious: Groups opposed to gun control could immediately contact members to urge them to vote, and there were no limits on how many times someone could respond. In fact, the show received about 100 times more votes than it usually receives when it does such surveys. It is likely, then, that this sample was not at all representative of the population of the city or even viewers of the program.

When local news programs, 24-hour news channels, or websites ask viewers to vote on a topic, the resulting samples are not representative of the population to which they are often trying to generalize. First, their viewers may be different from the U.S. population in meaningful ways (e.g., more Fox News viewers are conservative, more MSNBC viewers are liberal). Second, these programs and websites often ask about hot-button topics, things that people care passionately about, because that is what drives viewers and visitors to tune in. Questions about abortion, taxes, and wars tend to drive certain types of viewers to these informal “polls.” The results, whatever they may be, are biased because the sample consists primarily of people who have chosen to watch the program or visit the website, and they have chosen to vote because they are deeply interested in a topic.

You now have a great deal of information about methods for asking people about themselves. If you engage in this type of research, you will often need to design your own questions by following the guidelines described in this chapter and consulting sources such as Groves et al. (2009) and Fowler (2014). However, you can also adapt questions and entire questionnaires that have been used in previous research. Consider using previously developed questions, particularly if they have proven useful in other studies (make sure you do not violate any copyrights, however). A variety of measures of social, political, and occupational attitudes developed by others have been compiled by Robinson Page 157and his colleagues (Robinson, Athanasiou, & Head, 1969; Robinson, Rusk, & Head, 1968; Robinson, Shaver, & Wrightsman, 1991, 1999).

We noted in Chapter 4 that both nonexperimental and experimental research methods are necessary to fully understand behavior. The previous chapters have focused on nonexperimental approaches. In the next chapter, we begin a detailed description of experimental research design.

ILLUSTRATIVE ARTICLE: SURVEY RESEARCH

Every year hundreds of thousands of U.S. college students travel to Florida, Mexico, or similar sunny locales for spring break. For the most part, everybody involved—students, their universities, their parents, and the communities that they are traveling to—realizes that spring break can also be a dangerous time for college students: Students consume more alcohol during spring break and the risks associated with over consumption are more prevalent.

In a survey study conducted by Patrick, Morgan, Maggs, and Lefkowitz (2011), male and female college students completed a survey related to their perceptions of their friends’ “understandings” of spring break behaviors. That is, students were surveyed to see if their friends would “have their back” during spring break.

First, acquire and read the following article:

Patrick, M. E., Morgan, N., Maggs, J. L., & Lefkowitz, E. S., (2011). “I got your back”: Friends’ understandings regarding college student Spring Break behavior. Journal of Youth and Adolescence, 40, 108–120. doi:10.1007/s10964-010-9515-8

Then, after reading the article, consider the following:

1. What kinds of questions were included in the survey? Identify examples of each.

2. How and when was the survey administered? What are the potential problems with their administration strategy?

3. What was the nature of the sampling strategy? What was the final sample size?

4. What was the response rate for the survey?

5. Describe the demographic profile of the sample.

6. Do you think that these findings generalize to all college students? Why or why not?

7. Describe at least one finding that you found particularly interesting or surprising.