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PredictHistogram (DMX)

Topic Status: Some information in this topic is preview and subject to change in future releases. Preview information describes new features or changes to existing features in Microsoft SQL Server 2016 Community Technology Preview 2 (CTP2).

Returns a table that represents a histogram for the prediction of a given column.

PredictHistogram(<scalar column reference> | <cluster column reference>)

A scalar column reference or a cluster column reference. Can be used with all algorithm types except the Microsoft Association algorithm.

A histogram generates statistics columns. The column structure of the returned histogram depends on the type of column reference that is used with the PredictHistogram function.

Scalar Columns

For a <scalar column reference>, the histogram that the PredictHistogram function returns consists of the following columns:

  • The value that is being predicted.

  • $Support

  • $Probability

  • $ProbabilityVariance

    Microsoft data mining algorithms do not support $ProbabilityVariance. This column always contains 0 for Microsoft algorithms.

  • $ProbabilityStdev

    Microsoft data mining algorithms do not support $ProbabilityStdev. This column always contains 0 for Microsoft algorithms.

  • $AdjustedProbability

    The $AdjustedProbability column is an Analysis Services extension to the Microsoft OLE DB for Data Mining specification.

Cluster Columns

The histogram that the PredictHistogram function returns for a <cluster column reference> consists of the following columns:

  • $Cluster (represents the cluster name)

  • $Distance

  • $Probability

The following example returns the predicted state of the Bike Buyer column in a singleton query. The query also returns the top two most likely states of the Bike Buyer attribute, based on the adjusted probability obtained by using the PredictHistogram function.

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
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