For an interesting slant on what’s at stake for Democrats in the Wisconsin demonstrations, read Nate Silver’s “The Effects of Union Membership on Democratic Voting” at his Five Thirty Eight blog at The New York Times. Silver mines exit poll data and considers the propensity of union voters and households to vote for Democratic presidential and congressional candidates, noting:
In 2008, for instance, 59 percent of people in union households voted for Barack Obama, as compared to 51 percent of people in non-union households — a difference of 8 percentage points, according to the national exit poll. An extremely simple analysis might conclude, then, that the presence of the labor union vote boosted Mr. Obama’s share of the vote by slightly under 2 points overall: the 8 percentage point “bonus” that he received among union voters, multiplied by the 21 percent of the sample that was in labor union households, which is 1.68 percent.
The potential problem with this is that labor union voters are not distributed randomly throughout the population. Instead, virtually every other demographic variable — age, income, geography, occupation, gender, race, and so forth — is correlated in some with the likelihood of being in a union.
It could be, for instance, that because labor unions are concentrated in blue states, especially those in the Northeast and the industrial Midwest, the apparent influence of union membership on voting is really just a matter of geography. Alternatively, it could be that union members tend to vote Democratic despite having certain other characteristics that are ordinarily harmful to Democrats: for instance, union members tend to skew a bit older than the rest of the population and older voters normally tend to vote Republican. If so, the quick-and-dirty estimate from the exit poll might understate the effect of union membership on voting behavior.
Silver runs a logistic regression analysis on a large data sample from the National Annenberg Election Survey to help isolate the various factors. He presents a couple of bar charts which provide graphic depiction of the influence of 23 demographic variables on voters for president and congressional representatives, respectively. Silver calculates that members of unions and “union households” provided a 1.7 percent net advantage to Obama in ’08. However, if the National Exit Poll accurately reflected the union percentage of the turnout, Silver explains, the union member and household edge goes up to 2.4 percent. The figures were similar for congressional elections.
Further, in Silver’s analysis:
…Any votes that did not go to Mr. Obama instead went to Senator John McCain. Therefore, the impact on the margin between the two candidates was twice as large: not 2.4 points, but 4.8 points.
This is fairly meaningful. Of the last 10 elections in which the Democratic candidate won the popular vote (counting 2000, when Al Gore lost in the Electoral College), he did so by 4.8 points or fewer on 4 occasions (2000, 1976, 1960, 1948). So, while the impact of union voting is not gigantic in the abstract, it has the potential to sway quite a few presidential elections, since presidential elections are usually fairly close.
Silver then offers this interesting conclusion about the possible reverberations of Governor Walker’s and the GOP’s escalation of the political war against unions:
More tangibly, Republican efforts to decrease the influence of unions — while potentially worthwhile to their electoral prospects in the long-term — could contribute to a backlash in the near-term, making union members even more likely to vote Democratic and even more likely to turn out. If, for instance, the share of union households voting for Democrats was not 60 percent but closer to 70 percent, Republicans would have difficulty winning presidential elections for a couple of cycles until the number of union voters diminished further.
They could also energize union participation in campaign volunteer efforts. In the worst case scenario, Governor Walker may win his battle to eradicate most public employee unions. Even then, however, he may insure that it costs his party the presidency, and perhaps some other offices, in 2012.