¿Cómo y cuánto fallan los sondeos electorales?

Abstract

These pages present a simple methodology for evaluating the predictions of electoral opinion
polls. Both the graphic description and the numerical measurements proposed are based on
simulation methods. Special attention is paid to the problem of the estimation (warped) of the
distribution of parliamentary seats between the political parties using the d’Hondt law, and
the estimation of differences. The origin of the warp in estimation is studied and methods for
reducing it are suggested. In both cases, an analysis is made of the problem of the prior selection
of the size of the sample for guaranteeing a given margin of error. The results and predictions for
the Catalan elections of October 1999 and the March 2000 general elections illustrate the work
presented here.