Study of the effective freedom degree in Welch-Satterthwaite formula - To applied blood chemical analysis

摘要

The purpose of this research is utilizing ISO-GUM and making the result of blood chemical analysis (BCA) into the reference value that can be assurance, ISO-GUM recommends the new data analyzing method that shifts into exploratory data analysis (EDA)[1] from analysis of valiance (ANOVA). The proceed carry out into in ISO-GUM taking out an answer with three steps to obtaining the final measurement result. Three steps are standard uncertainty, combined uncertainty and expanded uncertainty. In ISO-GUM, for quality assurance (QA) of measurand, it is supposed that a confidence interval and a coverage factor (assurance factor) are important Coverage factor computes effective freedom degree with the formula of Welch-Satterthwaite, it shows in equation (3)[2]. A confidence interval is computed from statistical distribution elements. The reference value required for measurement exists acquired by sitting in the both side (upper and lower) limits of a confidence interval and is made to establish. Coverage factor is a confidence for also giving a margin to value in a confidence interval. Therefore it is a role with the effective freedom degree of coverage factor and the critical region of confidence interval for assurance performance of measured value [3] The effective freedom degree is promoted by ISO-GUM.