2.15. Table 2.2 shows the result of the 2000 Presidential election and the predictions of several organizations in the days before the election. The sample sizes were typically about 2000. The percentages for each poll do not sum to 100 because of voters reporting as undecided or favoring another candidate.

(a) What factors cause the results to vary somewhat among organizations?

(b) Identify the sampling error for the Gallup poll.

TABLE 2.2 Predicted Vote Poll Gore Bush Nader Gallup 46 48 4 Harris 47 47 5 ABC 45 48 3 CBS 45 44 4 NBC 44 47 3 Pew Research 47 49 4 Actual vote 48.4 47.9 2.7 Source: www.ncpp.org/