Public Perception of Mileage-Based User Fees (2016)

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9 CHAPTER TWO SETTING THE STAGE: OVERVIEW OF PUBLIC OPINION RESEARCH METHODS individuals surveyed accurately reflects the population of interest. If this challenge is met successfully with a prob- ability sampling method (often achieved with a random sampling design), the survey findings can be assumed with confidence to represent the views of the whole population under study. However, if the sampling design does not col- lect a representative sample of the population under study, the study findings cannot be assumed to reflect the views of the full population of interest. According to Cook (2011), it is becoming increasingly difficult, even among the top poll- ing firms, to ensure a representative sample and an adequate response rate. Another key factor to consider when assessing the results of a survey is the specific language used in asking questions. The way a person answers a question can change with even very small changes in the words or grammatical structure used, the question format (e.g., yes/no versus ranking), or even the order in which response options are presented. Thus, it is important to pay careful attention to the exact language used in survey questions in order to understand the precise opinions that respondents are expressing. QUALITATIVE RESEARCH Qualitative methods, which can include focus groups and semi-structured interviews, are other direct research meth- ods often used to learn about public opinion. This study identified primarily focus group studies, an approach in which a moderator poses questions and guides discussion among a small group of participants. Qualitative methods can be very effective for obtaining a detailed understanding of what peoples’ opinions are, as well as nuances about why they hold those opinions. Luntz (1994) notes that in contrast to surveys and other quantita- tive research, “Focus groups are centrally concerned with understanding attitudes rather than measuring them.” (Although Luntz refers to focus groups specifically, his comment applies to any qualitative method.) Compared with surveys, qualitative research designs can probe more deeply into participants’ experiences, perceptions, and feelings; the opinions they hold; and their knowledge of a topic (Pat- ton 2002). However, unlike well-designed survey research, the findings from qualitative studies are not generalizable This chapter sets the stage for the detailed analysis of MBUF research that follows in later chapters by presenting a very brief explanation of various methods for researching public opinion. Public opinion research can be categorized into two gen- eral approaches: (1) collecting opinions directly from the public and (2) systematic review of primary documents pro- duced externally to any research project. Examples of the former are polls or surveys, interviews, and focus groups. Examples of the latter include systematic collection and analysis of election results, media coverage, social media activity, and letters from constituents. An important consideration in evaluating public opinion research is to understand the potential biases that may exist in the collected information, as well as the strengths and weaknesses of different approaches. This report analyzes public opinion documented through formal research (par- ticularly surveys and focus groups) as well as public opinion as revealed in media stories. The remainder of this chapter presents a brief overview of key factors to consider in evalu- ating studies produced using those methods. In addition, the chapter explains the meta-analysis process used to evaluate the complete body of research synthesized in the report. PUBLIC OPINION SURVEYS Most formal assessment of public opinion is collected quanti- tatively, using surveys. These can be conducted face-to-face, by mail, by telephone, or electronically, and each method has its pros and cons. The survey mode itself—particularly whether it is self-administered or administered by an inter- viewer—can result in differences in responses, especially for personal or controversial topics (Pew Research Center 2015). For example, many people are less likely to admit to socially unacceptable opinions or behaviors if they are talking to a live interviewer than if they are recording their responses on paper or electronically. Also, individuals talk- ing to a live interviewer are less likely to reveal information they consider personal, such as income (Agrawal et al. 2015). The ability to generalize survey findings to the full pop- ulation is often the key advantage of a survey compared with qualitative public opinion research methods. A central challenge for survey research is ensuring that the sample of

10 to a larger population. For this reason, qualitative research is often conducted before a survey to develop survey topics and questions. CONTENT ANALYSIS OF MEDIA COVERAGE Another source of information that can be used to uncover public opinion on a topic is the media coverage of that issue. Decision makers often look to the media to learn what the public thinks about an issue. Media are also important because of what news the editors choose to cover and how they cover it. Editorial decisions define what issues are important and how those issues are framed (Terkidsen and Schnell 1997). While earlier research on the role of media in influencing public opinion concluded that the media sim- ply reinforced existing public opinion, more recent research suggests that the role is far more nuanced and powerful— that the media both reflect and shape public opinion (Terkid- sen and Schnell 1997). Media content analysis can be either quantitative (i.e., the number of times a topic is addressed) or qualitative (i.e., interpreting the themes and messages in the content) (Macnamara 2011). SECONDARY ANALYSIS OF EXISTING PUBLIC OPINION RESEARCH Another approach used to understand public opinion (see chapters three and four) is meta-analysis. In a meta-analysis, the researcher conducts a comprehensive analysis of studies on a particular topic to identify findings that emerge across multiple studies. A meta-analysis of survey data is quantita- tive, while a meta-analysis of focus groups or other qualita- tive research is conducted qualitatively. Both kinds are used in this report.