Predicting No Opinion in the Polls

On poll questions, levels of expressed public ignorance or indifference—No Opinion or Don't Know—can be explained in some part by certain properties of the questions pollsters ask, although the educational level of respondents is the single best predictor. No Opinion levels are analyzed in two large sets of recent poll questions published by Gallup and Harris. A measure of the language complexity of the questions shows no relationship to DK. Of the three other question predictors assessed, it is question content which best illuminates levels of No Opinion in both polls and points to some unique characteristics of each. The importance of question content is demonstrated in two additional sets of Gallup and Harris data. The more difficult kind of question content dominates in all four sets of poll questions examined.