Pollsters sometimes "oversample" a survey sub-population in order to increase the reliability of the results for that group. More interviews means less potential random sampling error. Before tabulating the data for the full sample, however, they "weight" back the oversample its correct proportion with the larger sample.

I checked with Gary Langer, the director of polling at ABC News, and he provided a few additional details. The ABC Polling Unit started with a nationally representative sample of 1,803 randomly selected adults interviewed between March 29 and April 4. Of these, 660 described themselves as baseball fans (on the survey's first question). Of these, 64 were African-American.

The pollsters wanted a bigger and more reliable sampling of African-Americans. So they continued calling from April 5 to April 22 and interviewed another 476 randomly sampled African Americans, of whom 139 were self-described baseball fans.

Thus (adding everything up), the ESPN/ABC survey interviewed 799 baseball fans, including 203 among African Americans. Before tabulating the data, however, they weighted the combined sample of 2,279 (the original 1,803 plus the oversample of 476 blacks) in a way that reduced the proportion of African-Americans to its correct value as determined by the U.S. Census.**

This practice is not at all unusual. The intent is to generate more statistically reliable results by race, not -- as Brown puts it -- to "generate racially charged results."