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一、概述此项工作的目的在于查明试验室制的混凝土立方试件强度值的分布及其标准差、变异系数和均值之间的关系,以便在有关试验数据的分析工作中有所依据。与此相联系的是加权最小二乘法在变异系数估计中的应用问题的探讨。我们在实验室里用相同的材料、不同的配比(不同的用水量和砂率)的混凝土拌合物制备了28组10×10×10(cm)的立方试件。每组数据构成一个样体,其容量n=25～30,基本上符合大样体的要求。这样,如果混凝土的强度值X服从正态分
I. Overview The purpose of this work is to ascertain the relationship between the distribution of the strength values of the concrete cubic specimens made in the laboratory and its standard deviation, coefficient of variation and mean value, so as to provide a basis for the analysis of relevant test data. Associated with this is the application of weighted least squares in the estimation of the coefficient of variation. We used the same material and different mix ratio (different water consumption and sand rate) in the laboratory to prepare 28 sets of 10×10×10 (cm) cubic specimens. Each set of data constitutes a sample, the capacity of which is n=25 to 30, basically meeting the requirements of the large sample. In this way, if the concrete strength value X obeys normal distribution