
Construction of the Index on Cultural Similarity
The Index on Cultural Similarity is a quantitative measure for the cultural similarity of groups of people in pair wise comparison. It has been constructed in the context of research on transnationalization and attempts of explaining the extensity and intensity of transnational links. Cultural similarity is time and again regarded as a relevant influence on explaining this links. The Index on Cultural Similarity allows a test of such assumptions for the quantitative macro research.
The index is based on an understanding of culture as “temporally relatively stable interpretation frames and values, which are shared by a group of people and are used for the interpretation of the world” (Gerhards 2000: 98, own translation). While this understanding of culture includes frames as well as values, the index focuses on the normative and potentially more controversial aspect of culture: values.
The construction of the index is based on questions used in the European Social Survey, which refer to the value dimensions suggested by Shalom Schwartz. These value questions are particularly useful for an index on cultural similarity as they cover the widest spectrum of dimensions on which people can have values. This broad coverage justifies to speak of an index on cultural similarity in general.
The value of the Index on Cultural Similarity for the cultural similarity of two countries is calculated by discriminant analysis of the populations of the two countries. Discriminant analysis is a statistical procedure to assess, on which variables and to which extent two previously defined groups differ. Using a predefined set of variables, the aim of the procedure is to predict the group to which a case belongs (Huberty 1994, Klecka 1993). In our case the procedure calculates inductively a discriminant function which best predicts the group membership of the cases based on the information provided in the variables on the Schwartz value questions.
How precise this predicition can be, how clearly the two groups can be distinguished based on these variables is indicated by the global discriminant measure, the Wilks’ Lambda. This Wilks’Lambda is defined as the index value for the compared pair of countries.
In conclusion: The value for the Index on Cultural Similarity is defined as the Wilks’ Lambda of a pairwise discriminant analysis of two groups of people over a set of value question with the broadest possible coverage.
Then Index on Cultural Similarity has range between 0 and 1 with 1 indicating the maximum similarity and 0 indicating the minimum similarity (or maximum dissimilarity).
The index turns out to be intertemporally stable. The correlations across the five rounds of the European Social Survey are as follows:
 Round 1  Round 2  Round 3  Round 4  Round 5 
Round 1  1 N=187  0,868 N=168  0,902 N=134  0,752 N=138  0,795 N=168 
Round 2  0,868 N=168  1 N=325  0,931 N=190  0,817 N=197  0,851 N=210 
Round 3  0,902 N=134  0,931 N=190  1 N=253  0,926 N=213  0,896 N=231 
Round 4  0,752 N=138  0,817 N=197  0,926 N=213  1 N=367  0,850 N=287 
Round 5  0,795 N=168  0,851 N=210  0,896 N=231  0,850 N=287  1 N=325 
By now the index construction as well as some comparisons with other measures have been published only in German in a journal article (Roose 2012)
and the paper "Der Index kultureller Ähnlichkeit. Konstruktion und Diskussion". English publications will follow in the nearer future.
References
 Gerhards, Jürgen (2000): Auf dem Weg zu einer theoriegesteuerten empirischen Kultursoziologie. In E. Barlösius, J. Gerhards, R. Hitzler, and S. Neckel (eds.): Empirische Kultursoziologie. Studienbrief Nr. 03706, Hagen: Fernuniversität.
 Huberty, Carl J. (1994): Applied Discriminant Analysis. New York u.a.: John Wiley & Sons.
 Klecka, William R. (1993): Discriminant Analysis. Newbury Park, London, New Delhi,: Sage.
 Roose, Jochen (2012): Die quantitative Bestimmung kultureller Unterschiedlichkeit in Europa. Vorschlag für einen Index kultureller Ähnlichkeit. Kölner Zeitschrift für Soziologie und Sozialpsychologie Vol. 64(2), pp. 361376.
 