Computes process mean and sigma and upper and lower natural process limits from process samples. The process sigma may be estimated in several ways. If the sample size is >1, either sample standard deviation s or range R can be used to estimate the process sigma. s or R are selected by the type input. If the sample size is 1, the moving range is used to estimate the process sigma. To calculate process mean and sigma on a 1D array, use the array builder primitive to create a 2D array and then wire to the samples X input. This VI interprets either a single column or a single row in a 2D array as sample size = 1.


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Inputs/Outputs

  • c2ddbl.png samples X —

  • cu16.png type: s/R (s) —

    (U16) - Type of process sigma computation to perform. s: base process sigma on mean sample standard deviation (default) R: base process sigma on mean sample Range Note: if sample size is 1, process sigma is based on mean moving Range.

  • ci32.png n for moving Range (2) —

    (I32) - This input is ignored unless the sample size i.e. all the points in the input array samples X is contained in a single row, or there is only one column in the input array, in which case the moving range is used as a basis for estimating process mean and sigma. Min value for n is 2, max is 25. By default n is 2.

  • cdbl.png sigma multiplier (3) —

    (DBL) - sigma multiplier for calculating upper and lower natural process limits. By default, sigma is multiplied by 3.0.

  • idbl.png process mean —

    (DBL) - mean of the process, estimated from X-bar-bar (or x-bar if sample size is 1).

  • idbl.png process sigma —

    (DBL) - sigma of the process, estimated from S-bar/c4 if type is S, R-bar/d2 if type is R, or mR-bar/d2 if sample size is 1.

  • idbl.png upper NPL —

    (DBL) - upper natural process limit of the process computed as process mean + sigma Multiplier * process sigma. By default this is process mean + 3.0*process sigma.

  • idbl.png lower NPL —

    (DBL) - lower natural process limit of the process computed as process mean - sigma multiplier * process sigma. By default this is process mean - 3.0*process sigma.