ASTM D4854-95

This guide is useful in estimating the variation due to lot sampling units, laboratory sampling units, and specimen selection and testing during the sampling and testing of a lot of material.

Estimates of variation from the several sources will make it possible to write sampling plans which balance the cost of sampling and testing with the desired precision of the plan.

This guide is useful in: (1) designing process controls and (2) developing sampling plans as parts of product specifications.

This guide can be used for designing new sampling plans or for improving old plans.

This guide is concerned with the process of sampling. This is unlike Practice D 2904 or Practice D 4467 which are concerned with the process of testing.

Studies based on this guide are applicable only to the material(s) on which the studies are made. If the conclusions are to be used for a specification, then separate studies should be made on three or more kinds of materials of the type on which the test method may be used and which produce test results covering the range of interest.

1.1 This guide serves as an aid to subcommittees in writing specifications and sampling procedures.

1.2 The guide explains how to estimate the contributions of the variability of lot sampling units, laboratory sampling units, and specimens to the variation of the test result of a sampling plan.

1.3 The guide explains how to combine the estimates of the variability from the three sources to obtain an estimate of the variability of the sampling plan results.

1.4 The guide is applicable to all sampling plans that produce variables data (Note 1). It is not applicable to plans that produce attribute data, since such plans do not take specimens in stages, but require that specimens be taken at random from all of the individual items in the lot. Note 0This guide is applicable to all sampling plans that produce variables data regardless of the kind of frequency distribution of these data, because no estimates are made of any probabilities.

1.5 This guide includes the following topics: