BS 2846-4 is an international standard that specifies the techniques required:
The techniques mentioned in BS 2846-4 are valid only if, in each of the populations under consideration, the sample elements are drawn at random and are independent. In the case of a finite population, elements drawn at random may be considered independent when the population size is sufficiently large or when the sampling fraction is sufficiently small (for instance smaller than 1/10).
BS 2846-4 on tests relating to means and variances is useful for:
The correct interpretation and presentation of test results have been assuming increasing importance in the analysis of data obtained from manufacturing processes based on sample determinations and prototype evaluations in the industry, commerce, and educational institutions. Much of the experimentation and testing is concerned with providing test results, which will give some idea of the value of a characteristic under investigation, or lend themselves to testing some theory concerning the characteristic. For example, it may be of interest to estimate the nitrogen content in a batch of some chemical compound and further test whether this content differs significantly from a required level.
BS 2846-4 is concerned with providing techniques that will answer these and similar questions. However, some caution is necessary for the application of the techniques, and in this respect, the general remarks should be read carefully and the validity of the assumptions checked. Using BS 2846-4 guidelines helps its users with accuracy, data representation and statistical methods of analysis.
ISO 2854