地震保険購入行動における曖昧性回避傾向の実証分析

Abstract

わが国の地震保険の普及率は低い。本稿では、その原因として地震保険の保険金支払いの曖昧性に着目した。保険の不払いリスクのある仮想的な地震保険に関する意識調査データを用い、曖昧性回避傾向を扱うことのできるマキシミン期待効用理論に基づいた、曖昧性プレミアム(曖昧性の存在によって追加的に生ずる保険料の支払い意思額)の金額の推定を試みた。その結果、保険金不払いリスクは曖昧性により過大に評価され、たとえ1%であっても地震保険の価値をほほ半減することが明らかになった。

Ambiguity of insurance payment in earthquake insurance can be one of main reasons of low purchase rate. We empirically investigate the influence of the ambiguity on the decision to buy hypothetical earthquake insurance and the relationship with individual characteristics based on MEU model using questionnaire data. The main results of this paper are summarized as follows. First, respondent’s preferences to the insurance with 1, 5, and 10% unreimbursement risk are generally inconsistent with expected utility theory. Second, respondents demanded more than 50% reduction in premium to offset each unreimbursement risk. Third, the ambiguity premium is larger in men who purchase earthquake insurance, have never received insurance payment, and distrust insurance companies than each correspondents, and increases with age, education level.