To describe the strength of two ceramic materials – quartz ceramics and glass ceramics OTM357 Nias – the weakest link model is used, described the two-parameter Weibull distribution function. The accuracy of estimates of parameters of statistical distribution strength depends on the number of samples tested and the evaluation method. The paper compares the evaluation of Weibull modulus, obtained by the method of least squares and maximum likelihood on different samples by volume generated by statistical tests. Estimates of the strength reliability of the antenna radome, depending on the size of the sample of material samples to be tested for strength in static bending.