Testing shelled corn for aflatoxin, Part III: Evaluating the performance of aflatoxin sampling plans

The effects of changes in sample size and/or sample acceptance level on the performance of aflatoxin sampling plans for shelled corn were investigated . Six sampling plans were evaluated for a range of sample sizes and sample acceptance levels. For a given sample size, decreasing the sample acceptanc e level decreases the percentage of lots accepted while increasing the perc entage of lots rejected at all aflatoxin concentrations, and decreases the average aflatoxin concentration in lots accepted and lots rejected, For a g iven sample size where the sample acceptance level decreases relative to a fixed regulatory guideline, the number of false positives increases and the number of false negatives decreases. For a given sample size where the sam ple acceptance level increases relative to a fixed regulatory guideline, th e number of false positives decreases and the number of false negatives inc reases, For a given sample acceptance level, increasing the sample size inc reases the percentage of lots accepted at concentrations below the regulato ry guideline while increasing the percentage of lots rejected at concentrat ions above the regulatory guideline, and decreases the average aflatoxin co ncentration in the lots accepted while increasing the average aflatoxin con centration in the rejected lots. For a given sample acceptance level that e quals the regulatory guideline, increasing the sample size decreases miscla ssification of lots, both false positives and false negatives.