Estimating Melamine Population Distributions Using Turnbull Estimator  

Oleh:

Tsai, Hsien-Tang ; Lo, Shih-Hsiung ; Wu, Tung-Ju

Jenis: Article from Proceeding
Dalam koleksi: Asian Network for Quality (ANQ) Congress 2011, Ho Chi Minh City, Vietnam, 27-30 September 2011, page 1-9.
Topik: Melamine; Limit of Detection; Left-censored Distribution; Turnbull Estimator
Fulltext: TW21.pdf (357.17KB)

Isi artikel

Studies of determinants of melamine detection frequently involve left-censored log-normally distributed data. Left censoring occurs when observations are below the analytical limit of detection (LOD). A common method of dealing with this type of data has been to substitute a value for the censored data followed by statistical analysis. Recently, Turnbull estimator methods have been employed to reduce bias associated with the substitution method. We compared substitution methods and Turnbull estimator with melamine test log-normally distributed data using SAS LIFEREG procedure. In these comparisons, the Turnbull estimator resulted in less bias and performed well even for censoring up to 88%, whereas the substitution method resulted in considerable bias.

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