Hockenbury Discovering Psychology 5th txtbk

24 CHAPTER 1 Introduction and Research Methods© The New Yorker Collection 2009, Joe Dator from cartoonbank.com. All rightsreserved.“Hi. I’m doing a survey. Do you have afew minutes to answer some questions?”Using random selection,approximately3,000 people werechosen for the sampleused in the NationalHealth and Social LifeSurvey (NHSLS). In thistable, you can see thatthe overall characteristicsof those in theNHSLS sample werevery representative ofthe U.S. population asa whole.Table 1.1Comparing the NHSLS Sampleand the U.S. PopulationNHSLS U.S.Sample PopulationGenderMen 44.6% 49.7%Women 55.4 50.3100% 100%Age18–24 15.9% 18.2%25–29 14.5 14.330–39 31.3 29.540–49 22.9 22.750–59 15.3 15.3100% 100%EducationLess thanhigh school 13.9% 15.8%High school orequivalent 62.2 64.0Any college 16.6 13.9Advanced 7.3 6.3100% 100%Marital StatusNever married 28.2% 27.7%Currentlymarried 53.3 58.3Divorced,separated 16.2 12.4Widowed 2.3 1.6100% 100%Race/EthnicityWhite 76.5% 75.9%Black 12.7 11.7Hispanic 5 9.0Other 3.3 3.3100% 100%SOURCE: Michael & others (1994).Surveys(A) Always (B) Sometimes (C) Never (D) Huh?A direct way to find out about the behavior, attitudes, and opinionsof people is simply to ask them. In a survey, people respondto a structured set of questions about their experiences, beliefs, behaviors,or attitudes. One key advantage offered by survey researchis that information can be gathered from a much larger group ofpeople than is possible with other research methods.Typically, surveys involve a carefully designed questionnaire in apaper-and-pencil format that is distributed to a select group of people.Computer-based or Internet-based surveys have become increasinglymore common. And, surveys are still often conducted over thetelephone or in person, with the interviewer recording the person’sresponses. As with paper-and-pencil surveys, the interviewer usually asks a structuredset of questions in a predetermined order. Such interview-based surveys are typicallymore expensive and time-consuming than questionnaire-based surveys.Surveys are seldom administered to everyone within the particular group or populationunder investigation. Instead, researchers usually select a sample—a segment ofthe larger group or population. Selecting a sample that is representative of the largergroup is the key to getting accurate survey results. A representativesample very closely parallels, or matches, the larger group on relevantcharacteristics, such as age, sex, race, marital status, and educationallevel.How do researchers select the participants so that they end upwith a sample that is representative of the larger group? The mostcommon strategy is to randomly select the sample participants.Random selection means that every member of the larger grouphas an equal chance of being selected for inclusion in the sample.To illustrate how random selection works, let’s look at how thesample was created for the landmark National Health and SocialLife Survey (NHSLS). Conducted by researcher Robert T.Michael and his colleagues (1994) at the University of Chicago,the NHSLS focused on the sexual practices of U.S. adults betweenthe ages of 18 and 59. Here is Michael’s description of howhis team used random selection to choose the survey participants:Essentially, we chose at random geographic areas of the country, usingthe statistical equivalent of a coin toss to select them. Within these geographicregions, we randomly selected cities, towns, and rural areas.Within those cities and towns we randomly selected neighborhoods.Within those neighborhoods, we randomly selected households. ... Ifthere were two people living in a household who were in our agerange, we flipped a coin to select which one to interview. If there werethree people in the household, we did the equivalent of flipping athree-sided coin to select one of them to interview.Notice that the participants who were interviewed in theNHSLS did not volunteer to participate in the survey. A specific individualwas randomly selected through the process described. Ifthat person refused to participate, someone else in the householdcould not substitute for that person. Using this random selectionprocess, more than 3,000 people were interviewed for the NationalHealth and Social Life Survey.How closely did the NHSLS sample match important characteristicsof the U.S. population? You can see for yourself by comparingthe two columns in Table 1.1. Clearly, the random selection processused in the NHSLS resulted in a sample that very closely approximatedthe characteristics of the U.S. population as a whole.