Proficiency Testing: Aerobic plate count in starch

Abstract

Proficiency testing program: Aerobic plate count in starch for year 2013, there were 140 laboratories participated and all test results were accepted. Sample used in this program was starch which was tested for homogeneity before sending and confirmed stability until the last day that participants were allowed to test.

Evaluation of laboratories was conducted by using assigned value derived from robust average of participants calculated by Algorithm A following ISO 13528:2005. The standard deviation for proficiency assessment, was set at 0.5 log cfu/g from expert judgments. Laboratories who have I z I score ≤ 2 are satisfactory, and 2 < | z | <3 are questionable while those who have | z | score ≥ 3 are outlier.

For this program, it was found that laboratories who have score ≤ 2 are 92.9%, those who have 2 < | z | < 3 are 5.7 % and I z | score ≥ 3 are 1.4.