***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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