Tham khảo tài liệu 'engineering statistics handbook episode 3 part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | . Analysis ENGINEERING STATISTICS HANDBOOK hW tools raids lỉEÂtCH BACK Nixf 2. Measurement Process Characterization . Characterization . What is a check standard . Analysis Short-term or level-1 standard deviations from J repetitions An analysis of the check standard data is the basis for quantifying random errors in the measurement process -- particularly time-dependent errors. Given that we have a database of check standard measurements as described in data collection where represents theyth repetition on the kth day the mean for the kth day is and the short-term level-1 standard deviation with v J -1 degrees of freedom is http div898 handbook mpc section1 1 of 3 5 1 2006 10 11 22 AM Drawback of short-term standard deviations Process level-2 standard deviation An individual short-term standard deviation will not be a reliable estimate of precision if the degrees of freedom is less than ten but the individual estimates can be pooled over the K days to obtain a more reliable estimate. The pooled level-1 standard deviation estimate with V K J -1 degrees of freedom is ÍJ_ệ 2 2s V À Jt-1 This standard deviation can be interpreted as quantifying the basic precision of the instrumentation used in the measurement process. The level-2 standard deviation of the check standard is appropriate for representing the process variability. It is computed with V K -1 degrees of freedom as . Analysis SEMMECH MOME rTOOLS IM SEARCH BACK NEXT http div898 handbook mpc section1 3 of 3 5 1 2006 10 11 22 AM
