1. Scope
1.1 This TAPPI Standard Practice provides a procedure for judging whether suspect test determinations
should be investigated further for possible rejection. A suspect determination (apparent outlier) is one that appears to
deviate markedly from other determinations on the same sample of material. An outlying determination (outlier) is a
suspect determination for which the deviation has, in fact, been found to be significant using an appropriate statistical
test.
1.2 Formal treatment of suspect test determinations, as specified in this document, is necessary only in
critical situations (e.g., very critical research) or when required by a product specification or an official test method.
1.2.1 Formal treatment of suspect test determinations and test results is highly desirable in studies for the
investigation of a test method (see TAPPI T 1200 "Interlaboratory Evaluation of Test Methods to Determine TAPPI
Repeatability and Reproducibility").
1.3 Both nonstatistical and statistical rules for dealing with suspect test determinations are given. Basically
no test determination should be accepted, no matter how correct the value appears to be, if it is known that a faulty
determination has been made, and no test determination should be completely rejected purely on a statistical significance
test.
1.4 The statistical tests described in this practice have been selected from a large number that are available.
They apply to the simplest kind of experimental data, that is, replicate determinations of some property of a given sample
of material.
NOTE 1: This practice applies to replicate test determinations, usually on several specimens taken under the same conditions and measured
in a brief period of time. A test result, obtained in accordance with a TAPPI Test Method, is usually one or the average of two or
more such test determinations (see definitions in TAPPI T 400 "Sampling and Accepting a Single Lot of Paper, Paperboard,
Containerboard or Related Product"). This practice allows the examination and possible elimination of suspect test determinations
(from sets of 3 to 30 determinations) before the calculation of the final test result.
NOTE 2: This practice may also be applied to suspect test results (by substituting the words "test results" for "test determinations"
throughout this document), when a laboratory must evaluate a large shipment requiring the determination and calculation of several
test results.
| Number of Pages : | 12 |
| Published : | 01/01/2009 |
