
ISO 13528 DIPERCENTAGE SCOREName:
The percentage difference score is then defined as
with x_{ref} denoting the "assigned value". The multiplication by 100 is to express the score as a percentage. The D_{i} and D_{i}% statistics are performance scores discussed in the ISO 13528 standard (2015 second edition page 25). The difference score is typically compared to a \( \delta_{E} \) value such that
indicates an action signal (i.e., unacceptable performance). In terms of the Di% score, this translates to
Note that Xref and DELTAe are not computed from the current data. The Xref is considered the "true" value (or the best guess for the true value). The ISO 13528 standard discusses numerous ways of determining this value. The DELTAe is an "acceptable" error. Although the ISO 13258 standard does not define a specific method for determing DELTAe, if estimates for the repeatability and reproducibility are available, then ISO 13528 suggests the following (p. 22)
where
Then
The justification for this is that this corresponds to an action signal of +/3 for zscores. In some cases, \( \sigma_{pt} \) may be based on fitness for purpose or data from prior rounds. The D_{i}% score is only one of several possible performance scores discussed in the ISO 13528 standard.
<SUBSET/EXCEPT/FOR qualification> where <x> is the response variable; <xref> is a parameter that defines the assigned value; <y> is a variable where the Di% score values are stored; and where the <SUBSET/EXCEPT/FOR qualification> is optional.
DIPERCENTAGE is a synonym for ISO 13528 PA SCORE DI PERCENTAGE is a synonym for DIPERCENTAGE
. Step 1: Read the Data . skip 25 read e2489a.dat labid y . . Step 2: Compute and print the Di percentage values . let xref = median y . let diperc= iso 13528 diperc y xref . set write decimals 3 print y diperc . . Step 3: Plot the Di percentage values . tic mark offset units screen tic mark offset 3 3 case asis label case ais title case asis title offset 2 . y1label D(i) % x1label Laboratory x2label Assigned Value: ^xref title D(i) % for E2489A.DAT line blank solid dash dash spike on line color black black red red . let sd = sd y let deltae = 3*sd let deltae = round(deltae,2) let ul = 100*deltae/xref let ll = ul . let xmax = maximum labid let xtemp = data 1 xmax let ymax = data ul ul let ymin = data ll ll let yzero = data 0 0 plot diperc labid and plot yzero xtemp and plot ymax xtemp and plot ymin xtempThe following output is generated  Y DIPERC  1.220 10.949 1.620 18.248 1.820 32.847 0.600 56.204 2.750 100.730 1.550 13.139 1.170 14.599 1.760 28.467 1.350 1.460 1.180 13.869 1.190 13.139 1.710 24.818 2.030 48.175 1.100 19.708 1.840 34.307 1.390 1.460 1.130 17.518 1.660 21.168 1.280 6.569 1.240 9.489 0.690 49.635 1.540 12.409 1.430 4.380 0.840 38.686 0.980 28.467 1.970 43.796 4.890 256.934 1.850 35.036 1.090 20.438 1.070 21.898  
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Date created: 04/11/2016 