Method and system for obtaining a specification limit value for use as acceptance criterion in a device acceptance test

Abstract

A method for obtaining at least one of an upper specification limit (USL) and a lower specification limit (LSL) as acceptance criteria in device acceptance testing, wherein the upper specification limit (USL) can be obtained by adding a deviation value to a center value (x50), and the lower specification limit (LSL) can be obtained by subtracting the deviation value from the center value, wherein the deviation value is based at least on a dispersion value (s), the method comprising: obtaining a set of parameter test result values ​​(steps 13, 15, 16), wherein each parameter test result value in the set of parameter test result values ​​is obtained by performing parameter tests on each of a plurality of test elements (2); obtaining the center value (x50) 50); Determine the deviation value from the parameter test result values, wherein determining the deviation value includes: determining a first parameter test result value (x0.621) corresponding to the percentile function value of the first percentile of the parameter test result value set; determining a second parameter test result value (x99.379) corresponding to the percentile function value of the second percentile of the parameter test result value set, wherein the first percentile is less than 50% and the second percentile is greater than 50%; and determining the dispersion value (s) based on both the first parameter test result value (x0.621) and the second parameter test result value (x99.379). A method of obtaining at least one of an upper and a lower specification limit value for use as acceptance criterion in a device acceptance test, wherein the upper specification limit value (USL) is obtainable by adding a deviation to a central value (x50) and the lower specification limit value (LSL) is obtainable by subtracting the deviation from the central value (x50), wherein the deviation is at least based on a spread value (s), comprises obtaining (13, 15,16) a set of parametric test result values, each obtained by carrying out the parametric test on a respective one of a plurality of test devices (2). The method further comprises obtaining the central value (x50) and determining, from the parametric test result values, the deviation. Determining the deviation comprises determining a first parametric test result value (x0.621) corresponding to a percentile function value at a first percentile of the set of parametric test result values and determining a second parametric test result value (x99.379) corresponding to a percentile function value at a second percentile of the set of parametric test result values, wherein the first percentile is below 50 % and the second percentile is above 50 %. The spread value (s) is determined on the basis of both the first parametric test result value (x0.621) and the second parametric test result value (x99.379).

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