This statistic comes from a recent commentary from the Pew Research Center For the People and the Press:
Party identification is not a particularly stable attitude. Many people go back and forth on how they regard themselves. When respondents are surveyed and then re-interviewed at a later date, substantial minorities give different answers. In November 2000, after the presidential election, Pew re-interviewed 1,113 voters who had participated in a survey in September of that year. In the period between the surveys, 18% of voters answered the party affiliation question differently than they had just two months earlier.
Whoa, that does seem pretty unstable. 18% switched in a period of just two months! A table which accompanied the commentary lays it all out, as well as similar data from 1992 (26%) and 1988 (16%). Since it's For the People, that table is reproduced at right, without persmission (hint on tables: the last row has the affiliation totals at first polling, the last column has totals at second polling, and the inner 3 by 3 matrix tracks the movement between groups). Pew seems to have the goods. Or at least they do until you recall one simple fact:
"Independent" is not a political party.
continued...
Upon closer inspection of the data tables, one discovers that the vast majority of those "substantial minorities" who changed identification did not actually switch parties, they rather moved back or forth between
one of the parties and Independent. In the 3 elections cited, the percentage who actually
switched parties was actually only
2-4% and in every case there was equal movement in both directions -
no net gain for either side on that account. Furthermore, the movement into and out of the Independent pool tends to balance out on each side, such that the overall proportion of self-described Democrats to Republicans is what you might call "particularly stable."
- 1988 (Oct-Nov) D:R went from 53.8 : 46.2 to 50.0 : 50.0 (-3.8 %)
- 1992 (Jun-Nov) D:R went from 55.2 : 44.8 to 55.2 : 44.8 (0.0 %)
- 2000 (Sep-Nov) D:R went from 55.4 : 44.6 to 55.9 : 44.1 (+0.5 %)
In conclusion, based on this data from Pew and on the long standing party ID numbers highlighted
elsewhere, it's very difficult to explain, for example, the recent Gallup poll that sampled at a D:R ratio of 41.8 : 58.2 (an
11.4% pickup from Pew's January-June 2004 numbers).
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