SAS Institute Alert Note SN-003568

From: SAS Technical Support (LISTSERV@VM.SAS.COM)
Date: Tue Nov 14 2000 - 14:08:16 EST

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                                     ***ALERT NOTE***
     SAS Note: SN-003568
      Product: ENT MINER
    Component: ASSOC

    Title:
    Specifying transaction window length may prevent some sequences from
    being detected

    Text:
    By default, the transaction window length on the Time Constraints tab of
    the Association Node is set to 'maximum duration.' If you change the
    setting to 'specify duration to use,' the node may fail to detect some
    sequences. If that happens, then all statistics and plots involving
    confidence or support will be incorrect. There is no obvious way to
    determine if the results are incorrect.

    Consider the following scenario. A customer makes six visits and
    purchases items A, B, C, D, and E in the following manner:
    Sequence Target
    1 A
    2 B
    3 C
    4 D
    5 A
    6 E
    Note that the target contains repeating values, A. If the transaction
    window length is set to a value less than or equal to the number of
    units until the next occurrence of the repeated value (4 in this
    example) then the node incorrectly fails to detect the sequence
    involving the repeated target value (A==>E).

    In order to determine if your results are incorrect, you will need to
    inspect the sequences for each customer. The bug occurs if
    1) the target contains repeating values and
    2) the transaction window length is set to a value which is less than or
       equal to the number of steps between two repeated values.

    Keywords:
    ASSOC ASSOCIATION SEQUENCE TRANSACTION WINDOW LENGTH CONFIDENCE SUPPORT
    LIFT INCORROUT INCORRSTAT

    Reported Releases:
    +------------REPORTED------------+ +------FIXED-----+
    System Version Level Version Level

    AIX/R 4.0
    DigitUnx 4.0
    HP800 4.0
    Solaris 4.0
    WIN/NT 4.0
    Win95 4.0

    Fixes Available: none

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