
ISO 13528 PA SCOREName:
with x_{ref} and \(\delta_{E}\) denoting the "assigned value" and the predefined allowance for measurement error, respectively. The multiplication by 100 is to express the score as a percentage. The Pa statistic is a performance score discussed in the ISO 13528 standard (2015 second edition pp. 2526). Values of Pa ≤ 100 and Pa ≥ 100 indicate an action signal (i.e., unacceptable performance). Note that x_{ref} and \(\delta_{E}\) are not computed from the current data. The x_{ref} 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 \( \delta_{E} \) is an "acceptable" error. Although the ISO 13258 standard does not define a specific method for determing \( \delta_{E} \), 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 Pa 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; <deltae> is a parameter that defines the DELTAe value; <y> is a variable where the Pa score values are stored; and where the <SUBSET/EXCEPT/FOR qualification> is optional.
PA is a synonym for ISO 13528 PA SCORE
. Step 1: Read the Data . skip 25 read e2489a.dat labid y . . Step 2: Compute and print the Pa values . let xref = median y let sd = sd y let deltae = 3*sd let deltae = round(deltae,2) . let pa = iso 13528 pa y xref deltae . set write decimals 3 print y pa . . Step 3: Plot the Pa values . tic mark offset units screen tic mark offset 3 3 case asis label case ais title case asis title offset 2 . y1label Percentage of Allowed Deviation (Pa) x1label Laboratory x2label Assigned Value: ^xref x3label DeltaE: ^deltae title Pa for E2489A.DAT line blank solid dash dash spike on line color black black red red . let xmax = maximum labid let xtemp = data 1 xmax let ymax = data 100 100 let ymin = data 100 100 let yzero = data 0 0 plot pa labid and plot yzero xtemp and plot ymax xtemp and plot ymin xtempThe following output is generated  Y PA  1.220 6.466 1.620 10.776 1.820 19.397 0.600 33.190 2.750 59.483 1.550 7.759 1.170 8.621 1.760 16.810 1.350 0.862 1.180 8.190 1.190 7.759 1.710 14.655 2.030 28.448 1.100 11.638 1.840 20.259 1.390 0.862 1.130 10.345 1.660 12.500 1.280 3.879 1.240 5.603 0.690 29.310 1.540 7.328 1.430 2.586 0.840 22.845 0.980 16.810 1.970 25.862 4.890 151.724 1.850 20.690 1.090 12.069 1.070 12.931  
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Date created: 04/11/2016 