GMAT考试：Argument写作范文四十

　　79.

　　In this editorial the author asserts that opinion polls are little better than random guesses to predicting outcomes of presidential elections. The authors basis for this assertion is that opinion polls measure only the preferences of voters at the time of the poll and that many voters change their preferences several time before voting―some remaining undecided until the moment they cast their vote. The authors reasoning is unconvincing in two critical respects.

　　First of alt the predictions based on random guessing are such that the greater the number of candidates, the less likely the prediction will be correct. The reason for this is obvious: random guessing requires that no outside information be allowed to influence the guess. Predictions based on opinion polls, on the other hand, will differ considerably from those based on random guesses simply because outside information will influence the result. For example, in a four-person race, random guessing would yield the correct prediction 25 percent of the time, whereas the percentage of correct predictions based on opinion polls would be much higher. The reason for this disparity is simple. Opinion polls enable us to narrow the choices. That is, opinion polls serve to reduce the number of viable candidates in the voters mind and thereby increase the likelihood that the prediction based on them will be correct.

　　In addition, while it is true that many voters change their minds several times before voting, and that some remain undecided until entering the voting booth, this is not true of everyone. Moreover, people who do change their minds frequently or wait until the last moment to decide have typically narrowed their choice to a few candidates

　　In conclusion, the author is mistaken in believing that random guessing would be as reliable as opinion polls in predicting the outcomes of presidential elections.

　　80

　　This editorial asserts that West Cambria should not change its highway speed limits because such changes adversely affect driver alertness and are therefore dangerous. To support this claim, the editorial cites statistics indicating that whenever East Cambria changed its speed limits, an average of 3 percent more automobile accidents occurred during the week after the change than during the week preceding it, even when the speed limit was lowered. As it stands, this argument suffers from three critical flaws.

　　First, it is unlikely that the brief one-week periods under comparison are representative of longer time periods. A difference of only 3 percent during one particular week can easily be accounted for by other factors, such as heavy holiday traffic or bad weather, or by problems with reporting or sampling. Had the editorial indicated that several speed-limitchanges in East Cambria contributed to the statistic, the argument would be more convincing; but for all we know, the statistic is based on only one such change. In any event, a one-week period is too brief to be representative because it is likely that accidents will occur more frequently immediately following the change, while people adjust to the new limit, than over the longer term when drivers have become accustomed to the change.

　　Secondly, the editorial fails to acknowledge possible differences in the types of accidents occurring before and after the change. It is possible that the accidents during the week before the change all involved fatalities, while those during the week after the change were minor fender-benders. If so, even though 3 percent more accidents occurred after the change, the authors argument that changing the speed limit increases danger for drivers would be seriously weakened.

　　Thirdly, the editorial fails to take into account possible differences between East and West Cambria that are relevant to how drivers react to speed-limit changes. Factors such as the condition of roads, average age and typical driving habits of residents, and weather patterns, would probably affect how well or how quickly drivers adapt to speed-limit changes. Thus, changing speed limits in East Cambria might be more dangerous than changing them in West Cambria.

　　In conclusion, the statistical evidence cited to support the argument is insignificant and probably unrepresentative. To better evaluate the argument, we need to know how many speed-limit changes contributed to the statistic and when the speed-limit changes were made. Finally, to strengthen the argument the author should show that East and West Cambria would be similarly affected by speed-limit changes.