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  1. OMG Issue

DMN13 — Make explicit reference to sample standard deviation

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  • Key: DMN13-131
  • Status: closed  
  • Source: Red Hat ( Matteo Mortari)
  • Summary:

    The specification in chapter "10.3.4.4 List functions" for built-in function stddev does not explicit if it's meant to be population or sample standard deviation.
    However based on the example provided "stddev( 2, 4, 7, 5 ) = 2.0816659994661" would indicate it is meant to be the sample standard deviation --which is undefined for a single 1 sample value

    In order to be explicit, it is suggested to change the table entry as:

    Name(parameters) Parameter Domain Description Example
    stddev( list )
    stddev( n 1 , ..., n n )    		 list is a list of number. n 1 ... n n are numbers. Returns the
    (sample) standard deviation of the list of numbers. If the list is empty,
    returns null. If the list contains only one number item, if n is a single number returns null.    		 stddev( 2, 4, 7, 5 ) =
    2.0816659994661
    stddev( [ 47 ] ) = null
    stddev( 47 ) = null
    stddev( [ ] ) = null
  • Reported: DMN 1.2b1 — Fri, 18 Jan 2019 15:30 GMT
  • Disposition: Resolved — DMN 1.3
  • Disposition Summary:

    Clarify the semantics of the stddev() function

    See revised text.
  • Updated: Mon, 30 Mar 2020 19:50 GMT