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$Support in Dmx query

    Question

  • After executing DMX query which uses PredictHistogram function I got results. In results $support is real number, for example 993.45632456. Is $support number of rows or cases which support results? How it could be real number?

    Thank you in advance

    Wednesday, August 21, 2013 10:10 AM

All replies

  • Support should be an integer for algorithms like Decision Tree.  For example, try this one for Adventure Works:

    SELECT
      [TM Decision Tree].[Bike Buyer],
      TopCount(PredictHistogram([Bike Buyer]),$AdjustedProbability,3)
    From
      [TM Decision Tree]
    NATURAL PREDICTION JOIN
    (SELECT 28 AS [Age],
      '2-5 Miles' AS [Commute Distance],
      'Graduate Degree' AS [Education],
      0 AS [Number Cars Owned],
      0 AS [Number Children At Home]) AS t

    Though, for Neural Network, support could be a fractional (meaning non-integer) value.  The same would be true for Logistic Regression:

    SELECT
      [TM Neural Net].[Bike Buyer],
      TopCount(PredictHistogram([Bike Buyer]),$AdjustedProbability,3)
    From
      [TM Neural Net]
    NATURAL PREDICTION JOIN
    (SELECT 28 AS [Age],
      '2-5 Miles' AS [Commute Distance],
      'Graduate Degree' AS [Education],
      0 AS [Number Cars Owned],
      0 AS [Number Children At Home]) AS t

     


    Mark Tabladillo PhD (MVP, SAS Expert; MCT, MCITP, MCAD .NET) http://www.marktab.net

    Tuesday, April 22, 2014 11:08 PM