P-Ⅲ型理论频率曲线参数估计——模糊极值法

A New Estimation Way of Pearson Type Ⅲ Distribution Parameter of Frequency Curve——Fuzzy Maximum Value Method

对一个实测的具体样本而言，我们总是期望由某种方法估计的参数所确定的Ｐ－Ⅲ型曲线能最优地拟合样本点据，并能对全体样本收到最好的平差功效。何谓“最优”、何谓“最好”却缺乏比较明确的数量概念，传统方法无一能对此问题作出有效的回答。正是基于水文现象的模糊性，提出了一种新的参数估计方法。

As far as an existing sample, we always expect that the Pearson type Ⅲ distribution curve which a method determines its parameters can optimally fits all sample points. But what is “optimal” or what is “best” are not very clear in mathematics, all kinds of existing ways can not successfully answer this question. In this paper, by considering hydrological fuzziness, a new estimation way of Pearson type Ⅲ distribution parameter of frequency curve is presented and a quantity standard is established, which is used to indicate the index describing the distance between all sample points and theoretical frequency curve.