AATCC Style Guide for Writing Test Methods and Procedures

AATCC M12-2020 pdf free.AATCC Style Guide for Writing Test Methods and Procedures.
23.1 Precision. A statement on precision allows potential users of the test 23.3.3 It is the policy of AATCC that no longstanding test methods will be dropped due to the lack of a precision statement.
213.4 In any AATCC test method that produces data in which more than one testing option is allowed, a precision statement based on the most used option satisfies the requirement. A committee may include precision for the other options, and is encouraged to do so, especially single laboratosy precision for each option available,
23.4 If the test result data are continuous variates, give the standard deviation or coefficient of variation, whichever is appropriate, and the applicable components of variance for each type of precision thai is reported. In any case, the precision statement shall give the 95% critical difference for sithin-luboruiorv and for bt’rween-Iaborutorv test data. If the precision is not the same for all materials, then give the precision for each material used in the intcrlaboratory test thai was used to obtain the precision measurements.
23.5 If the prevision varies with the test level, describe this variation.
23.6 Include oilier related information that may help users assess the degree of applicability of the statement to the materials of interest to them. It may be desirable to note the presence of other types of variability in test results on which information can be derived by supplemental studies.
237 Many rating scales in AATC(’ methods are limited and not continuous. If analysis of variance is used with such data, statistical errors may occur and the possibility should be noted in the precision statement. A subjective basis for evaluation the precision of test results may be offered as an alternative.
23.3.3 It is the policy of AATCC that no longstanding test methods will be dropped due to the lack of a precision statement.
213.4 In any AATCC test method that produces data in which more than one testing option is allowed, a precision statement based on the most used option satisfies the requirement. A committee may include precision for the other options, and is encouraged to do so, especially single laboratosy precision for each option available,
23.4 If the test result data are continuous variates, give the standard deviation or coefficient of variation, whichever is appropriate, and the applicable components of variance for each type of precision thai is reported. In any case, the precision statement shall give the 95% critical difference for sithin-luboruiorv and for bt’rween-Iaborutorv test data. If the precision is not the same for all materials, then give the precision for each material used in the intcrlaboratory test thai was used to obtain the precision measurements.
23.5 If the prevision varies with the test level, describe this variation.
23.6 Include oilier related information that may help users assess the degree of applicability of the statement to the materials of interest to them. It may be desirable to note the presence of other types of variability in test results on which information can be derived by supplemental studies.
237 Many rating scales in AATC(’ methods are limited and not continuous. If analysis of variance is used with such data, statistical errors may occur and the possibility should be noted in the precision statement. A subjective basis for evaluation the precision of test results may be offered as an alternative.
23.7.1 EXAMPLE:
X. 1 lnierlahoratorv Test Data—An interlaboratory test was run in 2OXX in which randomly-drawn samples of 2 materials were tested in each of 5 laboratories. Each laboratory used 2 operators. each of whom tested 4 specimens of each material. Calculation of components of variance was thought to be inappropriate due to the restricted and discontinuous rating scales, the non-linear relationships between the rating scales and color dii. ference units, and the increased variability in color difference units as the true value of the ratings decrease.
X.2 Precision— Based on the observations described in X.l and on general practice in the trade, a lot or consignments is generally considered as having a rating that is significantly worse than a specified value when a specimen from the lot or consignment has a rating for (insert here the name of the property) that is more than one-half step below the specilied rating on the Gray Scale for Color Change.
23.8 Preisürn S.ruienwni Format. The precision statcmcnt included in a tcst method must contain three basic sections:
(I) a brief description of the testing plan from which the data set was dcrivcd. citing the number of materials tcstcd, the number of laboratories participating, the number of operators per laboratory, the number of tests per operator. and any other pertinent inhlwmaLion: (2) a listing of the components of variance derived from the data set: and (3) a listing of the precision parameters calculated from the components of variance, usually in the form of critical differences, or confidence intervals.
23.9 The required statement of precision shall contain the information specified above or an explanation as to why a statement is not practicable. The absence of a statement on precision is not warranted if the reason is that an interlahoratory tcst has revealed that the precision is poor.
23.9.1 EXAMPLE: A precision statement is not applicable because data are not generated by this procedure.
23.9.2 EXAMPLE: Precision and Bias statements are not applicable because data are not generaced by this lest method.
23.10 Test methods that do not contain full precision statements should note the status and explanation.
23.10.1 1XAMPLE: Precision tbr this test method has not been established, Until a precision statement is generated for this test method, caution should be used when testing materials with this method. In most cases the use of standard statistical techniques in making any comparisons of test results for either within-laho— raton’ or bcrueen-Iahoratort averages have been tinmnd to be generally accepted.AATCC M12 pdf download.AATCC Style Guide for Writing Test Methods and Procedures