We begin the presentation of our empirical findings with some descriptive statistics about government composition. The mean party-political position of all cabinets in our dataset is 0.6 on the −5 to 5 left/right interval. Once we split our countries into the two groups, we see that all six majoritarian countries are located to the right of this mean (see Figure 1).

Fig. 1 Cabinet positions in majoritarian and PR countries

Note: mean left/right cabinet position with 95 per cent confidence interval. Cabinet positions are seats weighted left/right positions for all parties in cabinet and are calculated for each instance of cabinet formation. Left/right party position interval from −5 to 5 (left to right). Source: Döring and Manow (Reference Döring and Manow2013).

Figure 1 shows that all countries with majoritarian systems display a significant shift to the right at the cabinet level. Within that general rightward trend, Japan appears to be a particularly strong case. In combination with the controversial classification of the Japanese electoral system we decided to make prudent estimates and therefore exclude Japan from the following analysis. For PR countries we find that cabinets in Norway and Sweden are located clearly to the left of the centre, whereas all other PR countries are at the centre or somewhat to the right. However, comparing our two groups of countries we observe that almost all PR cabinets are to the left of cabinets in countries with majoritarian electoral rules. As a first observation we can therefore confirm the literature’s general finding that majoritarian electoral rules reveal a conservative bias.

What do we observe once we compare election, parliament, and government means for majoritarian and proportional systems (see Figure 2)? We find that majoritarian systems have a substantial right-wing bias at all three levels: (1) voters tend to vote more to the right than those in PR countries. Subsequently, on both the parliamentary and cabinet levels, the political mean moves even further to the right and we thus observe in countries with majoritarian rules, on top of the more conservative voting behaviour (2) a ‘mechanical effect’ when vote shares are translated into seat shares, plus (3) a further shift to the right when it comes to the formation of governments. Figure 2 does not tell us, though, whether this last effect is an additional or aggregate effect due to the preceding bias(es). In proportional systems, by contrast, the mean positions at all three levels do not differ greatly.

Fig. 2 Electoral, parliament and cabinet positions in majoritarian and PR countries

Note: mean left/right position of electorate (vote share of parties), parliaments (seat share of parties) and cabinets (seat share of cabinet parties) with 95 per cent confidence interval. Electoral and parliamentary positions are calculated for each election (396 observations) and cabinet positions for each instance of cabinet formation (622 observations). Japan is excluded from majoritarian countries. Left/right party position interval from −5 to 5 (left to right). Source: Döring and Manow (Reference Döring and Manow2013).

A simple regression model estimating the electoral position with a PR variable as well as estimating the parliamentary position with the electoral position and a PR variable shows the expected effects of electoral rules (see Table 2, Models 1a and 2a). The election mean in PR systems is to the left of majoritarian systems and the parliamentary mean shows an additional shift to the left.

Table 2 Impact of Electoral Rules on Election and Parliament Mean, ParlGov and CMP Data

Note: country-clustered robust standard errors in parentheses. Japan excluded (twenty-five elections); ParlGov-based left/right scale (−5 to 5); CMP left/right (‘rile’) scale (−100 to 100). *p