The arboretum procedure
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- Bu səhifədəki naviqasiya:
- The SEQUENCE Procedure Overview Procedure Syntax
- Procedure Syntax PROC SEQUENCE
- PROC SEQUENCE Statement Invokes the SEQUENCE procedure. PROC SEQUENCE
- DATA= SAS-data-set
- CUSTOMER Statement Specifies the ID variable that identifies each customer to be analyzed. Alias: CUST CUSTOMER
The SEQUENCE Procedure The SEQUENCE Procedure Overview Procedure Syntax PROC SEQUENCE Statement CUSTOMER Statement TARGET Statement VISIT Statement
Example 1: Performing a Simple 2-Item Sequence Discovery Example 2: Specifying the Maximum Number of Item Events and Setting the Lower Timing Limit
Copyright 2000 by SAS Institute Inc., Cary, NC, USA. All rights reserved. The SEQUENCE Procedure Overview The SEQUENCE procedure enables you to perform sequence discovery. Sequence discovery goes one step further than association discovery by taking into account the ordering or timing of the relationship among items, for example, "Of those customers who purchase a new computer, 25% of them will purchase a laser printer in the next quarter". To perform a sequence discovery, you must first run the ASSOCIATION procedure to create and output the data set of the assembled items. PROC SEQ produces rules similar to PROC RULEGEN, however the rules additionally imply an element of timing. A rule A==>B implies that event B occurred 'after' event A occurred. The visit or sequence variable is used for timing comparison. The sequence variable can have any numeric value, including date or time values. Transactions with missing sequence values are ignored entirely during the sequence computation. In order to determine the timing element, SEQUENCE utilizes a sequence variable or time-stamp that enables you to measure the time span from observation to observation. This procedure is useful for businesses such as banks or mail-order houses. Copyright 2000 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
The SEQUENCE Procedure Procedure Syntax PROC SEQUENCE <option(s)>; CUSTOMER variable(s); TARGET variable; VISIT variable /<visit-option(s)>; Copyright 2000 by SAS Institute Inc., Cary, NC, USA. All rights reserved. The SEQUENCE Procedure PROC SEQUENCE Statement Invokes the SEQUENCE procedure. PROC SEQUENCE <option(s)>; Required Arguments ASSOC= Specifies the SAS data set that was output from PROC ASSOC and which is also one of the inputs to PROC SEQ.
Specifies the input data source in its DMDB form. This data set is read in order to extract the timing information necessary to generate the sequence rules.
Identifies the metadata catalog associated with the input DMDB. Options NITEMS=integer Specifies the maximum number of events for which rules, or chains, are generated. If you request more than 2-event chains, (integer- 2) additional passes through the input file are required.
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Specifies the output data set to which the rules are written. The output data set has the following variables: RULE, COUNT, SUPPORT, CONF, ISET1, ISET2, ..., ISETn. RULE Contains the rule text, for example, A & B ==> C & D COUNT Contains the number of the transactions meeting the rule. SUPPORT Contains the percent of support, that is the percent of the total number of transactions that qualify for the rule. Definition: SUPPORT= COUNT/total, where total is the total number of transactions in the data set. The support level is an integer that represents how frequently the combination occurs in the database. CONF Contains the percent of confidence. Definition: CONF= COUNT/lhs_count where lhs_count is the number of transactions satisfying the left side of the rule. ISET1, ISET2,..., ISETn Contain, in order, the events that form the event chain. PROC SEQUENCE can detect multiple events occurring at the same time and can report them as rules of the type A & B ==> C & D. This means that events A and B occurred at the same time, followed by C and D, which occurred simultaneously afterwards. SUPPORT=integer Specifies the minimum number of transactions that must be considered in order for a rule to be accepted. Rules that do not meet the support level are rejected.
If not specified, SUPPORT is set to a number that is 2% of the total transaction count. Copyright 2000 by SAS Institute Inc., Cary, NC, USA. All rights reserved. The SEQUENCE Procedure CUSTOMER Statement Specifies the ID variable that identifies each customer to be analyzed. Alias: CUST CUSTOMER variable(s); Required Argument variable(s) Specifies the customer to be analyzed. Copyright 2000 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
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