Statistics Meeting Book (May 15, 2019)

C metamer: Report

AOAC International Interlaboratory Study Workbook

Version:

4.1

Blind (Unmatched) Replicates Study Reported Values

Seq.

Item

Symbol

Value 95% LCL 95% UCL

Name of study: Date of study: Sample/Matrix ID: Analyte:

JAOAC (2012) 95(2):411-418

1-Mar-2013

C02

OBPCP

Factor for Units of measurement: Metamer to analyze (C or pC): True value (blank if not known):

0.01

C

1 Total number of laboratories 2 Total number of replicates

p

13 26

Sum(n(L)) XBARBAR

3 Overall mean of all data (grand mean) 4 Repeatability standard deviation 5 Interlaboratory standard deivation 6 Bias estimate (Measured - True) DERIVED VALUES: 7 Reproducibility standard deviation 8 Root-mean-square-total-error 9 Repeatability relative standard deviation 10 Reproducibility relative standard deviation

0.0951 0.0921 0.0981 0.00127 0.00092 0.00205 0.00510 0.00365 0.00841

s(r) s(L)

b

s(R) rmse

0.00525

RSD(r) RSD(R)

1.34 5.52 0.97

11 HORRAT value

Roughly consistent with RSD(r) = 1.49% and RSD(R) = 5.57% given in article. Differences may be due to rounding of data values.

11

copyright 2018 by Least Cost Formulations, Ltd., all rights reserved.

pC metamer • Useful across concentration for micro to trace analyte (C < 0.10 g/g) across a wide range of concentrations. • Results for different concentrations generally comparable. • Data subject to platykurtosis (failure of normal distribution assumption). Skew in C metamer is usually corrected by pC transform. • Example: pH transform of hydrogen ion concentration. copyright 2018 by Least Cost Formulations, Ltd., all rights reserved. 12