The CPM Procedure

Output 4.1.1: Network Showing Task Relationships in Activity-on-Node Format

The following DATA step reads the project network in AON format into a SAS data set named WIDGET. The data set contains the minimum amount of information needed to invoke PROC CPM, namely, the ACTIVITY variable, one or more SUCCESSOR variables, and a DURATION variable. PROC CPM is invoked, and the Schedule data set is displayed using the PRINT procedure in Output 4.1.2. The Schedule data set produced by PROC CPM contains the solution in canonical units, without reference to any calendar date or time. For instance, the early start time of the first activity in the project is the beginning of period 0 and the early finish time is the beginning of period 5.

/* Activity-on-Node representation of the project */
   data widget;
   format task $12. succ1-succ3 $12.;
   input task & days succ1 & succ2 & succ3 & ;
   datalines;
Approve Plan   5  Drawings      Study Market  Write Specs
Drawings      10  Prototype     .             .
Study Market   5  Mkt. Strat.   .             .
Write Specs    5  Prototype     .             .
Prototype     15  Materials     Facility      .
Mkt. Strat.   10  Test Market   Marketing     .
Materials     10  Init. Prod.   .             .
Facility      10  Init. Prod.   .             .
Init. Prod.   10  Test Market   Marketing     Evaluate
Evaluate      10  Changes       .             .
Test Market   15  Changes       .             .
Changes        5  Production    .             .
Production     0  .             .             .
Marketing      0  .             .             .
;

/* Invoke PROC CPM to schedule the project specifying the */
/* ACTIVITY, DURATION and SUCCESSOR variables             */
proc cpm;
   activity task;
   duration days;
   successor succ1 succ2 succ3;
   run;

title 'Widget Manufacture: Activity-On-Node Format';
title2 'Critical Path';
proc print;
   run;

Alternately, if you know that the project is to start on December 1, 2003, then you can determine the project schedule with reference to calendar dates by specifying the DATE= option in the PROC CPM statement. The default unit of duration is assumed to be DAY. The architecture of PROC CPM enables you to include any number of additional variables that are relevant to the project. Here, for example, you may want to include more descriptive activity names and department information. The data set DETAILS contains more information about the project that is merged with the WIDGET data set to produce the WIDGETN data set. The ID statement is useful to carry information through to the data set. Output 4.1.3 displays the resulting output data set.

data details;
   format task $12. dept $13. descrpt $30. ;
   input task & dept $ descrpt & ;
   label dept =  "Department"
         descrpt = "Activity Description";
   datalines;
Approve Plan  Planning       Finalize and Approve Plan
Drawings      Engineering    Prepare Drawings
Study Market  Marketing      Analyze Potential Markets
Write Specs   Engineering    Write Specifications
Prototype     Engineering    Build Prototype
Mkt. Strat.   Marketing      Develop Marketing Concept
Materials     Manufacturing  Procure Raw Materials
Facility      Manufacturing  Prepare Manufacturing Facility
Init. Prod.   Manufacturing  Initial Production Run
Evaluate      Testing        Evaluate Product In-House
Test Market   Testing        Mail Product to Sample Market
Changes       Engineering    Engineering Changes
Production    Manufacturing  Begin Full Scale Production
Marketing     Marketing      Begin Full Scale Marketing
   ;

/* Combine project network data with additional details */
data widgetn;
   merge widget details;
   run;

/* Schedule using PROC CPM, identifying the variables */
/* that specify additional project information        */
/* and set project start date to be December 1, 2003  */
proc cpm data=widgetn date='1dec03'd;
   activity task;
   successor succ1 succ2 succ3;
   duration days;
   id dept descrpt;
   run;

proc sort;
   by e_start;
   run;

title2 'Project Schedule';
proc print;
   id descrpt;
   var dept e_: l_: t_float f_float;
   run;