Simon Hug and Tobial Schulz, "Left-Right Positions of Political Parties in Switzerland," Party Politics, 13 (May 2007), 305-330.

Second paragraph:
In this article, we explore whether using fixed party positions in Switzerland from one point in time is adequate for testing particular predictions of theoretical models. More precisely, we assess whether left-right positions of Swiss political parties have changed over time. Given the need for precise measures of party positions, we discuss various possible measurement strategies and provide estimates for the policy positions of Swiss parties. These estimates exclusively concern the placement of parties on a left-right scale, which most authors consider to be the dominant policy dimension (e.g. Budge et al., 1987; Laver and Hunt, 1992). Some of the measures proposed are difficult to use in assessing changes of party positions over time, so we discuss various limitations and offer ways of taking advantage of the different measurement strategies.

Figures and Tables:
Figure 1. Swiss party positions derived from elite and expert surveys
Figure 2. Swiss party positions derived from party manifestos
Figure 3. Swiss party positions derived from party manifestos
Figure 4. Median positions of Swiss parties (roll-call data; N = 3026)
Table 2. Content of first dimension: roll-call data
Table 3. Recommendation data: Fit of dynamic cubic model (1971 to 2003)
Figure 5. Swiss party positions derived from recommendations (N = 295)
Table 4. Content of first dimension1: vote recommendation data
Table 5. Unity of the parties on the cantonal level (roll-call data)
Table 6. Unity of the parties on the cantonal level (recommendations)
Table 7. Parties and their abbreviations
Table 8. Left-right positions of Swiss parties in surveys

Last Paragraph:
Looking at the cohesion of the Swiss parties, we find results that are in line with earlier findings. The leftist PSS is one of the more cohesive parties whether we consider vote recommendations or roll-call votes. Interesting are the trends in the cohesion we uncovered for the UDC. While this party was affected by some divisions in the 1990s, more recently these differences in opinion appear to have been reduced slightly, if one looks at the roll-call data. Hence, for most purposes the parties in federal Switzerland appear to be sufficiently cohesive such that one may neglect cantonal differences for most purposes of research.