I’m by no means a polling or statistics expert but I know that when you read a report about a poll, the numbers are useless unless you get some idea of how the data were collected and computed. And we haven’t even got to the margin of error-thing yet.
Anyway, Mark Blumenthal has collected and published this set of data about the composition of the samples different polling organisations have used in the run-up to the Democratic primary in Texas.
To quote Blumenthal’s own observation:
…the results show considerable variation, particularly on the Latino or Hispanic percentage of the samples, which vary from a low of 24-26% (ARG) to a high of 39% (Post/ABC). Other categories also show wide variation including the percentages of African Americans (from 14% to 23%), women (from 51% to 58%) and voters over 65 years of age (from 15% to 30%; comparisons by age categories are especially difficult, since no two pollsters report exactly the same age breaks).
Worth remembering when you read the varying predictions of the Texas primary.