December 1, 2004

by Reb Yudel
Bush and the Jewish Vote: Mystery Pollster Weighs In

Last week I linked to Joe Shick's argument that the exit polls have underestimated Jewish support for Bush. I also raised the question with the Mystery Pollster, who wrote back to me today:

Basically, your hunch is correct, although I am in no position to evaluate Shick's argument (not yet anyway).

I am told that at least one "well known pollster" will soon release results of a study on this question, and I'll post on it when it happens.

At that point, I'll try to study the data a bit more, but this is a very tricky issue involving both sampling and measurement issues (such as that age old favorite, who is a Jew?).

M.P. addresses the question in today's posting entitled NEP Revises Texas Hispanic Estimates, from which I extract some paragraphs:
One thing I can explain is the special challenge exit polls face when it comes to small subgroups like Latinos and Jewish voters.

The reason is the whole issue of "cluster sampling."

Exit polls must sample voters in clusters: They randomly sample precincts first, then voters at precincts. In a cluster sample, characteristics or opinions that tend to "cluster" geographically tend to have higher rates of sampling error.

The reason is not all that mysterious.

Consider the example of Jewish voters in Ohio (a demographic that once included the Mystery Pollster and still includes all of his family, so he speaks from some experience). Most Jews in Ohio live in a few suburbs east of Cleveland and few neighborhoods near Columbus and Cincinnati that cumulatively represent (at most) 3-5% of the state. If the Ohio exit poll sampled only 100 precincts, then most of the Jewish subsample would have come from, at most, 3-5 precincts.

Now throw in a kicker: Orthodox Jews tend to be more politically conservative and tend to live among other Orthodox Jews in even more concentrated geographic areas within the Jewish Community.

Thus, the odds are good that the exit poll sample will either over or underestimate the share of Orthodox Jews depending which 3-5 precincts get randomly selected. The same problems occurs with Cuban and non-Cuban Latinos in Florida.

So the bottom-line: The potential for error is much greater for a highly clustered demographic group. The fewer clusters in the sample relative, the greater the chance for this sort of error.

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