サーヴェイ実験による経済評価の質問形式の検討―党派性バイアスと個人志向性バイアスの検証への含意―

抄録

　In order to obtain voters' sociotropic economic evaluations during election surveys in Japan, a question worded "how are the overall business conditions [keiki] at the present time in Japan?" has long been used. The question could instead ask for an objective evaluation of the national economic condition by being phrasing as "how is the economy [keizai] in the country as a whole? Would you say that over the past year the nation's economy has gotten worse, stayed about the same, or gotten better?" In the first question, the choice of the phrase "overall business conditions" could invite subjective and even egotropic evaluations. Furthermore, a simple question about either business or economic conditions cannot educe which economic policy field respondents recall while answering. In the present study, we assumed that the ex-ante partisanship of those who respond with government policy in mind affects their sociotropic economic assessments more strongly than those who do not, and a partisan bias therefore exists. Further, literature has pointed out that subjects use their pocketbook conditions for information cues to evaluate socioeconomic conditions, and to confirm the presence of this egotropic bias, whether respondents tend to evoke their own economic situation as reflective of the nations socioeconomic policy must be confirmed.

　The method used to address the above concerns was an online-survey experiment comparing the conventional question based on business conditions (control), the question based on economic conditions (treatment 1), and a branching question (treatment 2). The branching question first asks survey respondents to choose and rank four appropriate fields of economic policy, and then asks them to evaluate the actual situations in these four fields. Based on this experiment, involving three types of questions, and by testing the hypotheses with a conventional difference-of-means test and structural equation modeling, it was found that (1) the most recalled economic field is personal income when respondents were asked about economic policy; (2) both partisan and egotropic biases are likely to exist among Japanese voters; and (3) both partisan and egotropic cues are triggered in those who think of the economic field as related to the Cabinet's policy emphases, than those who do not.