在上一次的GMAT写作中，说到了与数据相关的逻辑错误中的偏采样错误，今天我们继续来谈谈此类错误中的“不充分采样错误（The Insufficient Sample Fallacy）”。在argument中会引用一些来自某项涉及“样本”的研究、调查或民意测验的统计数据，接着就会得出与该样本代表的更大的集体或人口相关的结论。但是为了使某个统计样本能准确地反映一大群人的情况，该样本必须满足以下两条标准：
The following appeared in a newspaper story giving advice about investments.
“As overall life expectancy continues to rise, the population of our country is growing increasingly older. For example, over twenty percent of the residents of one of our more populated regions are now at least 65 years old, and occupancy rates at resort hotels in that region declined significantly during the past six months. Because of these two related trends, a prudent investor would be well advised to sell interest in hotels and invest in hospitals and nursing homes instead.”
The author provides no evidence to support the claim that the population as a whole is aging and that the hotel occupancy rate in general is declining. The example cited, while suggestive of these trends, is insufficient to warrant their truth because there is no reason to believe that data drawn from this unnamed region is representative of the entire country. For example, if the region from which the data was gathered was Florida, it would clearly be unrepresentative. The reason for this is obvious. Florida is populated by a disproportionate number of retired people over 65 years old and is a very popular vacation destination during the winter months. Moreover, resort hotel occupancy in Florida typically declines significantly during the summer months.