How many laboratories, samples and replicates does a committee need to run an ILS?
For guidance on the number of laboratories refer to E691 Under no circumstances should the final statement of precision of a test method be based on acceptable test results for each material from fewer than 6 laboratories. This would require that the ILS begin with 8 or more laboratories in order to allow for attrition. For guidance on the number of samples refer to E691 An ILS of a test method should include at least three materials representing different test levels, and for development of broadly applicable precision statements, six or more materials should be included in the study. For guidance on the number of replicates refer to E691 The number may be as small as two when there is little danger that a test unit will be lost or questionable test results obtained, or as many as ten when test results are apt to vary considerably.
