# Commission Decision of 12 August 2002 implementing Council Directive 96/23/EC concerning the performance of analytical methods and the interpretation of results (notified under document number C(2002) 3044) (Text with EEA relevance) (2002/657/EC), Chapter 3.3.: CALCULATION EXAMPLE FOR RUGGEDNESS TESTING OF MINOR CHANGES ACCORDING TO THE YOUDEN APPROACH (16)

Extent: E+W+S+N.I.

Comparison of averages (A)
AA = Σ(Ai)/4
Compare the averages of the capital letters (AA to AG) with the averages of their corresponding small letters (Aa to Ag). If a factor have an effect, the difference will be significant larger than the differences of the other factors.
A robust method should not be affected by changes encountered almost certainly between laboratories.
If there is no outstanding difference, the most realistic measure of the random error is given by the seven differences.
AB = Σ(Bi)/4
AC = Σ(Ci)/4
AD = Σ(Di)/4
AE = Σ(Ei)/4
AF = Σ(Ei)/4
AG = Σ(Gi)/4
Aa = Σ(ai)/4
Ab = Σ(bi)/4
Ac = Σ(ci)/4
Ad = Σ(di)/4
Ae = Σ(ei)/4
Af = Σ(fi)/4
Ag = Σ(gi)/4
Differences (Di)
Squares of differences (Di2)
Da = A – a = Σ(Ai) – Σ(ai)
Da2 = value a
Db = B – b = Σ(Bi) – Σ(bi)
Db2 = value b
Dc = C – c = Σ(Ci) – Σ(ci)
Dc2 = value c
Dd = D – d = Σ(Di) – Σ(di)
Dd2 = value d
De = E – e = Σ(Ei) – Σ(ei)
De2 = value e
Df = F – f = Σ(Fi) – Σ(fi)
Df2 = value f
Dg = G – g = Σ(Gi) – Σ(gi)
Dg2 = value g

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Source: https://www.legislation.gov.uk/eudn/2002/657/annex/chapter/3.3 (the official version)
Page: https://openlegislation.uk/eu-decision-2002-657/annex/chapter-3.3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.