Response Options and the Measurement of Political Knowledge

By many measures, the public knows little about politics. But just how little people seem to know depends on the questions that are put to them. In particular, knowledge levels seem higher when people are asked closed- rather than open-ended questions. In turn, differences between estimated knowledge levels are sometimes attributed to fundamental differences between these types of questions. Building on this previous research, the present study uses a pre-registered experiment conducted with a representative national sample to shed new light on the relationship between question form and knowledge measurement. The authors find that inferences about political knowledge depend less on fundamental differences between open- and closed-ended questions than on two little-appreciated aspects of survey design: the number and difficulty of the response options that accompany closed-ended questions. These aspects of survey design have large effects. Scholars who use the same questions with different response options may reach substantively different conclusions about the public's levels of knowledge.