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| Weighted Mean for Correlation Data Influenced by Common Components |
| YUAN Zun-dong,WANG Chi,LIN Yan-dong,LI Yan-hua |
| National Institute of Metrology, Beijing 100013, China |
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Abstract By contrasted with the weighted mean method (WMM) for uncorrelated data, the WMM for a set of correlated data with common components is studied. A simple method with manipuility is presented for estimating the uncertainty of common component of traceability chain. The weights for calculating mean, which are derived, are the uncertainties of only uncorrelated components, not the ones of entire data. The uncertainty of common component for the mean is inherent, which is not decreased with increasing the number of averaged data. It not only influences the weights and thus the mean, but also leads an underestimation for the uncertainty of mean to neglect the influence of the correlation on the weights. Take a pressure comparison for instance, the estimations for the uncertainty of common component are illustrated and their results calculated with different estimated values are given.
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2012, Vol. 33 
