Understanding cumulative risk

This paper summarizes the theory of simple cumulative risks—for example, the risk of food poisoning from the consumption of a series of portions of tainted food. Problems concerning such risks are extraordinarily difficult for naı¨ve individuals, and the paper explains the reasons for this difficulty. It describes how naı¨ve individuals usually attempt to estimate cumulative risks, and it outlines a computer program that models these methods. This account predicts that estimates can be improved if problems of cumulative risk are framed so that individuals can focus on the appropriate subset of cases. The paper reports two experiments that corroborated this prediction. They also showed that whether problems are stated in terms of frequencies (80 out of 100 people got food poisoning) or in terms of percentages (80% of people got food poisoning) did not reliably affect accuracy.

Electoral reform in Europe since 1945

This article surveys and analyses democratic electoral reform in Europe since 1945 in order to pursue three issues. First, it seeks understanding of the processes through which electoral systems change. Second, it asks how the incidence of these processes varies over context and time. Third, it investigates whether there are relationships between the nature of the processes through which electoral system change occurs and the electoral reforms that are thereby adopted. The analysis suggests, most importantly, that electoral system changes occur via multiple contrasting processes, that there is a tendency towards increasing impact of mass opinion upon these changes, and that this is beginning to generate a trend towards greater personalisation in the electoral systems adopted. These findings are, however, preliminary; the article is intended to encourage further discussion and research.