Middle alternatives and measurement validity: a recommendation for survey researchers

ABSTRACT

Questionnaires routinely measure unipolar and bipolar constructs using rating scales. Such rating scales can offer odd numbers of points, meaning that they have explicit middle alternatives, or they can offer even numbers of points, omitting the middle alternative. By examining four types of questions in six national or regional telephone surveys, this paper found that omitting the middle alternative and forcing respondents to pick a side compromised data quality, for questions presenting two conditions with middle option ‘about equally,’ and for quasi-bipolar questions with middle option ‘fair.’ In addition, omitting the middle alternative never helped improve data quality for a variety of unipolar questions. Lastly, there is a marginally significant improvement in terms of data quality for bipolar questions with middle option ‘neither good nor bad’ when offering a follow-up asking whether they lean one way or the other or whether they are genuinely in the middle.

KEYWORDS:

• Midpoint
• measurement validity
• questionnaire design
• branching
• satisficing

Acknowledgments

The authors thank Josh Pasek, Gaurav Sood, Bo MacInnis, Neil Malhotra, and the anonymous referees and editors for their valuable advice.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Rui Wang

Rui Wang is an Assistant Professor at the School of Journalism and Communication of Beijing Normal University in China. She received her Ph.D. in Communication from Stanford University in 2016. Her research focuses on public opinion, deliberation, and survey methodology.

Jon A. Krosnick

Jon A. Krosnick is the Frederic O. Glover Professor in Humanities and Social Sciences, Professor of Communication, Political Science, and (by courtesy) Psychology at Stanford University. He conducts research on attitude formation, change, and effects, on the psychology of political behavior, and on survey research methods.