WHY THE DEMOCRAT-REPUBLICAN PARTISANSHIP GAP VARIES FROM POLL TO POLL

Polls taken in late 1980 and 1984 varied by up to 20 points in the spread they reported between Democratic and Republican identifiers. We found three systematic and sizable differences across polls: polls that sample only voters, polls that emphasize "today" or the present in their question wording, and polls that are taken close to election day (at least in circumstances like those of 1984) tend to favor the party currently advantaged in the presidential race. A favorite recent pastime of political poll watchers is charting the changing fortunes of Republicans versus Democrats in surveys of party identification. And rightly so, because 1984 data appear to show a genuine gain in the ratio of Republican to Democratic identifiers. It may be, as one recent analyst put it, "that a [partisan] realignment is no longer incipient, but upon us" (Epstein, 1985:52). While a realignment may indeed be underway, a problem for anyone involved in political tealeaf reading is that there is more than one leaf to read. Poll data from late 1984, much of which is summarized in a recent issue of Public Opinion, showed a spread of anywhere from zero to 19 percentage points between Democratic and Republican identifiers. In late 1980 the polls were somewhat less variable, but they still showed the Democratic-Republican gap ranging from 14 to 24 percentage points (Public Opinion, Oct./Nov. 1985:56-57). In this article we explain some of this variability by identifying three factors (in addition to STEPHEN BORRELLI and BRAD LOCKERBIE are doctoral candidates in the Department of Political Science, University of Iowa. RICHARD G. NIEMI iS Professor of Political Science, University of Rochester. The authors wish to thank members of the various survey organizations for their assistance in gathering and verifying the data used in this article, and Michael Lewis-Beck for his helpful comments on the analysis. Public Opinion Quarterly Volume 51:115-119 ? 1987 by the American Association for Public Opinion Research Published by The University of Chicago Press / 0033-362X/87/0051-01/$2.50 This content downloaded from 207.46.13.75 on Sat, 03 Sep 2016 04:02:19 UTC All use subject to http://about.jstor.org/terms 116 Stephen Borrelli, Brad Lockerbie, and Richard G. Niemi the change between 1980 and 1984) that account for differences in the results from one poll to another. Factors Affecting Party Identification Responses The first factor likely to affect partisanship levels is when, in relation to the election, the poll was conducted. Polls taken on or near election day reflect presidential voting results to a greater degree than polls taken long before or after (Converse, 1976:123-30). Respondents asked for their party identification on election day presumably downplay their long-term loyalties if those feelings conflict with their current voting behavior. Although we as analysts know that partisanship and the vote are separable, some respondents may think that they are actually being asked how they voted. In 1980 and 1984 we would expect a poll taken close to election day to report a relatively narrow gap between Democratic and Republican identifiers, reflecting the large Republican vote margins in those elections. We might also expect proximity to election day to have a more pronounced effect in the latter year because there was less voter uncertainty in 1984.1 The second relevant factor is the population sampled or reported in a given poll. Exit polls, of course, sample only people who have actually voted. Of the polls that do not restrict themselves to voters, some (such as Harris) typically report results for "likely voters"; others (such as Yankelovich, Skelly, and White) sample registered voters; still others base results on complete cross-section samples. Polls limited to actual voters are more likely to reflect current election sentiments. With Reagan's 1980 and 1984 victories, the Democratic-Republican partisanship gap reported by exit polls should be smaller than the gap reported by the more inclusive polls. The third important factor is the wording of the partisanship question. A question beginning "as of today" is likely to tap short-term feelings associated with the election, thereby showing the smallest partisan gap. A preface of "generally" or "usually," and especially "regardless of how you may vote" (or "may have voted in the past") should focus attention away from the present election. In 1980 and 1984, therefore, questions referring to "today" should yield smaller