Reevaluation of tolerances for noxious weed seeds
2000
Elias, S.G. | Liu, H. | Schabenberger, O. | Copeland, L.O.
This paper examines the background and validity of the current noxious weed seed tolerances used by the Association of Official Seed Analysts and tolerances for counts of other seeds used by the International Seed Testing Association. The effects of the two types of statistical errors (Type I and II), their relationship to sample size, and their impact on both the seed seller and consumer are discussed. This study suggests that the formula for the normal approximation of the Poisson distribution used to calculate the present AOSA noxious weed seed tolerances in the AOSA Rules for Testing Seeds is in error. Furthermore, probabilities of the Poisson distribution can be derived directly without the need for the approximation for a wide range of means (average number of noxious weed seeds). Alternative tolerances are suggested based on appropriate statistical procedures. The problem of a zero standard for prohibited noxious weed seeds is discussed. No statistical basis or special tolerance exists for enforcement of labeling information for seeds of "undesirable agricultural species."
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