钉螺在自然状态下多呈负二项分布,一种效果好尤其是具有远期效果的灭螺措施,可能会打破钉螺的这种自然分布状态。反之,灭螺前后不同时期钉螺分布特征的变化,似可反映某种措施的灭螺效果。鉴于钉螺的负二项分布特征,可以通过对每框钉螺数经对数转换后的正态性检验得以验证,因此,本次利用2002年10月20日～11月22日在安徽省石台县进行的现场药物灭螺试验结果,依据 Snails in the natural state mostly negative binomial distribution, a good effect, especially with the long-term effects of snail-killing measures, snails may break this natural distribution. On the contrary, before and after snail snail changes at different periods of snail distribution characteristics may seem to reflect a measure of snail control effect. Due to the negative binomial distribution characteristics of snails, it can be verified by the normality test after logarithmic conversion of snail number in each box. Therefore, using this method in Shitai, Anhui Province from October 20 to November 22, 2002, County on-site drug snail test results, based on