Kenneth Janda, Robert Harmel, Christine Edens and Patricia Goff, "Changes in Party Identity: Evidence from Party Manifestos," Party Politics , 1 (April, 1995), 171-196.

First Paragraph:
We define the identity of a political party as the image that citizens have in mind when they think about that party. Political parties develop their identities through the different faces they present to the public while in and out of government. A party's human face is shaped by the characteristics of its leaders and supporters. During the 1980s, for example, the British Conservative Party was personified by Margaret Thatcher, while Labour was seen as closely linked to trade union leaders. Occasionally, the public reacts to a party's organizational face: one party can come across as centralized and highly disciplined while another is seen as disorganized or even fragmented. Of course, parties also create a policy face by the positions they espouse on political issues. Sometimes parties initiate a policy facelift by changing or repackaging their policies, altering their identity by moving to the left, or getting tough on crime, or embracing family values, or championing nationalism, or stressing some other policy shift.

Figures and Tables:
Table 1: Pairs of elections (29) in the study.
Figure 1: Percent of sentences assigned to 37 coding categories in the election manifestos of the German Social Democratic Party in 1983 and 1987.
Table 2: Central tendency and variation in correlations for party manifestos, by party.
Figure 2: Histogram of 78 correlations between party platforms in adjacent elections.
Table 3: Summary of election classification by party.
Table 4: Classification of elections by parties.
Table 5: The 19 lowest correlations between election manifestos in adjacent years.
Table 6: Number of quasi-sentences in the 'short' German manifestos.
Table 7: Rankings of intervening election outcome and correlations between election manifestos.

Last Paragraph:
This paper addressed the question: why do parties change their policy identities? The manifesto project data for eight parties in Britain, Germany and the USA were analyzed to determine how much parties changed their emphasis on particular issues in their manifestos between elections held from the 1950s to the 1980s. Specifically, the percentages of sentences accorded to 54 issue categories in one election were correlated with the percentages discussed in the subsequent election. The mean correlation between adjacent election manifestos was .41 for 78 cases. The hypothesis being tested was that electorally motivated parties were most likely to change their policy identities following disappointing or calamitous elections. The 17 lowest correlations between manifestos for these parties were analyzed according to the outcome of the preceding election. These instances represented the most striking cases of change in the packaging of election manifestos. Of these 17 cases, 15 followed election performances that were independently classified as disappointing or calamitous. Our findings suggest that while substantial change in issue emphases may occur in the absence of poor electoral performance, poor performance may be needed to produce extreme attempts to change party identity through election manifestos. While election defeat is surely not a sufficient cause for party change, and may stop short of being necessary for at least some types and levels of change, this study provides new evidence of an important role for poor electoral performance in explaining when and why parties change.