目前,我国冶金产品化学分析方法所用允许误差(公差),常常参考国外同类分析方法的误差而定,多数情况下是采用“商定误差”。即由少数单位根据实际经验共同协商而确定的误差,它部份地反映了国内外化学分析水平的现状,对产品质量的管理起了一定的作用。但由于没有严格的定义与计算方法,对允许差概念的理解很不统一,在使用上往往造成混乱。近年来,一些单位在建立标准分析方法和标样定值过程中,深感“商定误差”不能满足形势发展的需要,因而研究和提出了一些制定允许差的统计方法和各种方案,并在小范围内试用, At present, the allowable errors (tolerances) used in the chemical analysis of metallurgical products in our country are often determined by reference to the errors of similar foreign analytical methods. In most cases, the “agreed error” is used. That is, the error determined by a few units based on actual experience and consultation, partly reflects the status quo of chemical analysis at home and abroad and plays a certain role in the management of product quality. However, because there is no strict definition and calculation method, the understanding of the concept of permissive difference is not uniform, and the use often leads to confusion. In recent years, some units in the establishment of standard analytical methods and standard setting process, the deep “agreed error” can not meet the needs of the development of the situation, and thus study and put forward some allowable statistical methods and programs to develop, and in Trial within a small area,