Are the Sweden Democrats really Sweden’s largest party? A maximum likelihood ratio test on the simplex

  • Jakob Bergman Department of Statistics Lund University School of Economics and Management Box 743, SE-22007 Lund, Sweden
  • Björn Holmquist Department of Statistics Lund University School of Economics and Management Box 743, SE-22007 Lund, Sweden
Keywords: Isometric logratio transformation, Largest party, Maximum likelihood ratio test, Political polls, Polls, Sweden, Simplex

Abstract

In August 2015 a Swedish newspaper claimed that the Sweden Democrats were the largest political party in Sweden based on the results of single poll. We ask ourselves if this is a correct conclusion, considering the fact that the three largest parties in the poll were of roughly the same size. We analyse the parameter space and identify the subspace where the Sweden Democrats are the largest party. Using this we construct a maximum likelihood ratio test and derive its distribution under the null hypothesis. We finally apply our test to the data and obtaining a p-value between 0.09 and 0.14 are able to refute the claim in the newspaper. Based on the available data one cannot draw the conclusion that the Sweden Democrats are the largest party in Sweden.

Issue
Section
Working Papers in Statistics