Johansson A S, Whitaker T B, Giesbrecht F G, Hagler W M, Young J H
US Department of Agriculture, Agricultural Research Service, North Carolina State University, Raleigh 27695-7625, USA.
J AOAC Int. 2000 Sep-Oct;83(5):1270-8.
The suitability of several theoretical distributions to predict the observed distribution of aflatoxin test results in shelled corn was investigated. Fifteen positively skewed theoretical distributions were each fitted to 18 empirical distributions of aflatoxin test results for shelled corn. The compound gamma distribution was selected to model aflatoxin test results for shelled corn. The method of moments technique was chosen to estimate the parameters of the compound gamma distribution. Mathematical expressions were developed to calculate the parameters of the compound gamma distribution for any lot aflatoxin concentration and test procedure. Observed acceptance probabilities were compared to operating characteristic curves predicted from the compound gamma distribution, and all 18 observed acceptance probabilities were found to lie within a 95% confidence band. The parameters of compound gamma were used to calculate the fraction of aflatoxin-contaminated kernels in contaminated lots. At 20 ppb, it was estimated that about 6 in 10,000 kernels are contaminated.
研究了几种理论分布对预测脱壳玉米中黄曲霉毒素检测结果的观测分布的适用性。将15种正偏态理论分布分别拟合到脱壳玉米黄曲霉毒素检测结果的18种经验分布上。选择复合伽马分布来模拟脱壳玉米的黄曲霉毒素检测结果。选用矩估计法来估计复合伽马分布的参数。推导了数学表达式，用于计算任何批次黄曲霉毒素浓度和检测程序下复合伽马分布的参数。将观测到的接受概率与根据复合伽马分布预测的操作特征曲线进行比较，发现所有18个观测到的接受概率都在95%置信区间内。复合伽马分布的参数用于计算受污染批次中受黄曲霉毒素污染的玉米粒比例。在20 ppb时，估计每10000粒玉米粒中约有6粒受到污染。
