MORE ON THE ZOGBY TROOP POLL

Mystery Pollster has a reality-based critique. Here's a snippet:

So what can we say about the degree to which the Zogby survey used random probability sampling to survey U.S. troops? Again, as I wrote earlier in the week, the method Zogby used to gain access to the undisclosed locations constrained his ability to select them. The selection was not random, but since he will not disclose the locations, we cannot take their identity into account in evaluating the results. The release specifies a sampling error of 3.3% (a statistic that, given the sample size, is based on the assumption of simple random sampling), but that margin is a bit deceiving. Plus or minus 3.3% compared to what? All we know for certain is that the poll was not a random sample of the population of all U.S. troops in Iraq.

As to the selection of respondents at those unspecified locations, we also do not know the procedures used to select respondents. Again, I did not press Zogby on the details of those procedures in our conversation because I would not have been able to report them here. I believe MPs readers deserve more than "trust me" as an explanation. Obviously, for me to speculate now about what Zogby might have done would require getting into the details I promised I would not reveal.