Optimal jury design for homogeneous juries with correlated votes

In a homogeneous jury, in which each vote is correct with the same probability, and each pair of votes correlates with the same correlation coefficient, there exists a correlation-robust voting quota, such that the probability of a correct verdict is independent of the correlation coefficient. For positive correlation, an increase in the correlation coefficient decreases the probability of a correct verdict for any voting rule below the correlation-robust quota, and increases that probability for any above the correlation-robust quota. The jury may be less competent under the correlation-robust rule than under simple majority rule and less competent under simple majority rule than a single juror alone. The jury is always less competent than a single juror under unanimity rule.     

Bounds on the competence of a homogeneous jury

In a homogeneous jury, the votes are exchangeable correlated Bernoulli random variables. We derive the bounds on a homogeneous jury’s competence as the minimum and maximum probability of the jury being correct, which arise due to unknown correlations among the votes. The lower bound delineates the downside risk associated with entrusting decisions to the jury. In large and not-too-competent juries the lower bound may fall below the success probability of a fair coin flip—one half, while the upper bound may not reach a certainty. We also derive the bounds on the voting power of an individual juror as the minimum and maximum probability of her/his casting a decisive vote. The maximum is less than one, while the minimum of zero can be attained for infinitely many combinations of distribution moments.     

Aggregation of correlated votes and Condorcet’s Jury Theorem

This paper proves two theorems for homogeneous juries that arise from different solutions to the problem of aggregation of dichotomous choice. In the first theorem, negative correlation increases the competence of the jury, while positive correlation has the opposite effect. An enlargement of the jury with positive correlation can be detrimental up to a certain size, beyond which it becomes beneficial. The second theorem finds a family of distributions for which correlation has no effect on a jury’s competence. The approach allows us to compute the bounds on a jury’s competence as the maximum and minimum probability of it being correct for a given individual competence and dependence structure.     

Deaths from Alcohol and Violence in Moscow: Socio-economic Determinants

Objective: To examine the association between accidental, violent and alcohol related adult mortality in the Russian capital and socio-economic status characteristics such as educational status, occupational group and marital status.Data and methods: individual death records for Moscow City for the years 1994 and 1995, for 86121 deaths between the ages of 20–59. Proportional mortality analysis was used to compare trends for alcohol related deaths and accidental and violent deaths (representing 5 and 28% of all deaths in this age group), with multiple controls consisting of deaths from cancer at various sites.Results: The probability of death from alcohol related diseases increased as education level decreased, with those men failing to complete secondary education over two and a half times as likely to die from these causes than men with higher education. Blue collar workers were also much more likely to die from these causes than white collar workers. Marriage had a marked protective effect for both men and women.Conclusion: Despite 75 years of official egalitarian ideology, there are marked socio-economic differentials in mortality in Russia. For the causes of death analysed, socio-economic mortality differentials were greater for women than for men.     

A new estimate of Ukrainian population losses during the crises of the 1930s and 1940s

Ukraine experienced two very acute demographic crises during the Soviet era: the 1933 famine and the Second World War. While different estimates of total losses have been produced previously, we have tried here to distinguish the specific impact of the crises on mortality from their impact on fertility and migration. Taking into account all existing sources of registered data and estimates, a painstaking reconstruction of annual demographic changes has been produced and complete annual life tables have been computed for the years 1926-59. Life expectancy at birth fell to a level as low as 10 years for females and 7 for males in 1933 and plateaued around 25 for females and 15 for males in the period 1941-44.     

The exact bias of the Banzhaf measure of power when votes are neither equiprobable nor independent

This paper discusses a numerical scheme for computing the Banzhaf swing probability when votes are neither equiprobable nor independent. Examples indicate a substantial bias in the Banzhaf measure of voting power if neither assumption is met. The analytical part derives the exact magnitude of the bias due to the common probability of an affirmative vote deviating from one half and due to common correlation in unweighted simple-majority games. The former bias is polynomial, the latter is linear. A modified square-root rule for two-tier voting systems that takes into account both the homogeneity and the size of constituencies is also provided.     

Epidemiological transition of mortality curves in terms of the Brass logit system

Historical life tables for developed countries are analysed in order to present the epidemiological transition in terms of Brass's logit system. The results of this analysis are used to determine the range of the two Brass model parameters consistent with historical life tables. This range also includes human life tables that could have been observed in pre-transitional stages or could occur in the future.