Multidimensional Scaling

The Swedish political parties are positioned in a twodimensional space based on the like/dislike survey questions in the Comparative Study of Electoral Systems (CSES) dataset (wave 4).

The relative positions of the Swedish political parties are determined in two stages:
1. A line-of-sight procedure
2. Multidimensional Scaling.

The line-of-sight procedure use independent individual preference ratings to generate stimulus object similarity data. The line-of-sight procedure is argued to be more appropriate than the more commonly used Pearson product-moment correlations and sums of squared differences between pairs of objects to evaluate the similarities of the stimulus objects (Rabinowitz 1976).

The Multidimensional Scaling (MDS) produces a geometric model of proximities data from (dis)similarity data among a set of stimulus objects. The MDS generates a point in a space for each stimulus where similar stimulus objects are positioned close to each other.

The resulting graph for the Swedish political parties are presented below.

Political Parties
FI: Feministiskt Initiativ
V: Vänsterpartiet
MP: Miljöpartiet
S: Socialdemokraterna
C: Centern
FP: Folkpartiet
M: Moderaterna
SD: Sverigedemokraterna
KD: Kristdemokraterna

References
Rabinowitz, G. Psychometrika (1976) 41: 349. doi:10.1007/BF02293560