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A critical analysis of sampling variance estimators of Ingamells and Gy

Authors
Journal
Geochimica et Cosmochimica Acta
0016-7037
Publisher
Elsevier
Publication Date
Volume
57
Issue
16
Identifiers
DOI: 10.1016/0016-7037(93)90336-u

Abstract

Abstract A comparison between the formulae proposed by Ingamells (1976, 1978) and Gy (1982) for assay variance estimation is presented, considering the statistical assumptions underlying their derivations. It is shown that Ingamells' formula is based on assumptions that are inconsistent and cannot be realised in practice. The application of the more general estimator of Gy (1982) to a gold sampling problem is considered in detail, and it is thereby demonstrated that the Gy (1982) estimator has wide validity. The Gy (1982) approach is extended to estimate assay distribution skewedness, and a criterion is developed to permit estimation of the sample mass required to reduce assay distribution skewedness.

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