【国外标准】 Standard Practice for Sampling Wool for Moisture

5.1 This recommended practice furnishes directions for the sampling of wool of the various forms indicated in Section 1, in order that correct probability statements may be made about the relationship between the sample mean and the population mean. If these statements are to be correct, certain conditions, which are stated, must hold.5.2 This recommended practice requires that a deliberate act of randomization be performed so that all potential sampling units have approximately the same chance of being taken and no sampling unit is deprived of its chance of being taken.5.3 In any case where insufficient information about the variability of the sampling units within the lot is available, directions are given for calculating confidence limits for the sample mean so that a correct probability statement can still be made.1.1 This practice covers the design of a sampling plan to be used to obtain samples for the determination of the moisture content of grease wool, scoured wool, carded wool, garnetted wool, wool top and intermediate products, and rovings.1.2 Directions are given for the designation of sampling units, calculation of the number of sampling units required to achieve a preselected precision and confidence level or, alternatively, for calculating the confidence limits for the mean based on the variability of the sample tested.NOTE 1: This practice for devising a sampling plan is intended for use in connection with Test Method D1576 or Test Method D2462. The sampling of raw wool for the determination of clean wool fiber present is covered in Practice D1060.1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.