Example 2.6: Changing Duration Units

The CPM Procedure

Example 2.6: Changing Duration Units

This example illustrates the use of the INTERVAL= option to identify the units of duration to PROC CPM. In the previous examples, it was assumed that work can be done on the activities all seven days of the week without any break. Suppose now that you want to schedule the activities only on weekdays. To do so, specify INTERVAL=WEEKDAY in the PROC CPM statement. Output 2.6.1 displays the schedule produced by PROC CPM. Note that, with a shorter work week, the project finishes on March 9, 1992, instead of on March 1, 1992.

   proc cpm data=widget out=save
        date='2dec91'd interval=weekday;
      activity task;
      succ     succ1 succ2 succ3;
      duration days;
      run;

   title 'Changing Duration Units';
   title2 'INTERVAL=WEEKDAY';
   proc print;
      id task;
      var e_: l_: t_float f_float;
      run;

Output 2.6.1: Changing Duration Units: INTERVAL=WEEKDAY

Changing Duration Units

INTERVAL=WEEKDAY

task	E_START	E_FINISH	L_START	L_FINISH	T_FLOAT	F_FLOAT
Approve Plan	02DEC91	06DEC91	02DEC91	06DEC91	0	0
Drawings	09DEC91	20DEC91	09DEC91	20DEC91	0	0
Anal. Market	09DEC91	13DEC91	20JAN92	24JAN92	30	0
Write Specs	09DEC91	13DEC91	16DEC91	20DEC91	5	5
Prototype	23DEC91	10JAN92	23DEC91	10JAN92	0	0
Mkt. Strat.	16DEC91	27DEC91	27JAN92	07FEB92	30	30
Materials	13JAN92	24JAN92	13JAN92	24JAN92	0	0
Facility	13JAN92	24JAN92	13JAN92	24JAN92	0	0
Init. Prod.	27JAN92	07FEB92	27JAN92	07FEB92	0	0
Evaluate	10FEB92	21FEB92	17FEB92	28FEB92	5	5
Test Market	10FEB92	28FEB92	10FEB92	28FEB92	0	0
Changes	02MAR92	06MAR92	02MAR92	06MAR92	0	0
Production	09MAR92	09MAR92	09MAR92	09MAR92	0	0
Marketing	10FEB92	10FEB92	09MAR92	09MAR92	20	20

To display the weekday schedule on a calendar, use the WEEKDAY option in the PROC CALENDAR statement. The following code sorts the Schedule data set by the E_START variable and produces a calendar shown in Output 2.6.2, which displays the schedule of activities for the month of December.

   proc sort;
      by e_start;
      run;

   /* truncate schedule: print only for december */
   data december;
      set save;
      e_finish = min('31dec91'd, e_finish);
      if e_start <= '31dec91'd;
      run;

   title3 'Calendar of Schedule';
   proc calendar data=december schedule weekdays;
      id e_start;
      finish e_finish;
      var task;
      run;

Output 2.6.2: Changing Duration Units: WEEKDAY Calendar for December

Changing Duration Units

INTERVAL=WEEKDAY

Calendar of Schedule

  ----------------------------------------------------------------------------  
  |                                                                          |  
  |                              December  1991                              |  
  |                                                                          |  
  |--------------------------------------------------------------------------|  
  |    Monday    |   Tuesday    |  Wednesday   |   Thursday   |    Friday    |  
  |--------------+--------------+--------------+--------------+--------------|  
  |       2      |       3      |       4      |       5      |       6      |  
  |              |              |              |              |              |  
  |              |              |              |              |              |  
  |              |              |              |              |              |  
  |              |              |              |              |              |  
  |+==============================Approve Plan==============================+|  
  |--------------+--------------+--------------+--------------+--------------|  
  |       9      |      10      |      11      |      12      |      13      |  
  |              |              |              |              |              |  
  |              |              |              |              |              |  
  |+==============================Write Specs===============================+|  
  |+==============================Anal. Market==============================+|  
  |+================================Drawings================================>|  
  |--------------+--------------+--------------+--------------+--------------|  
  |      16      |      17      |      18      |      19      |      20      |  
  |              |              |              |              |              |  
  |              |              |              |              |              |  
  |              |              |              |              |              |  
  |+==============================Mkt. Strat.===============================>|  
  |<================================Drawings================================+|  
  |--------------+--------------+--------------+--------------+--------------|  
  |      23      |      24      |      25      |      26      |      27      |  
  |              |              |              |              |              |  
  |              |              |              |              |              |  
  |              |              |              |              |              |  
  |+===============================Prototype================================>|  
  |<==============================Mkt. Strat.===============================+|  
  |--------------+--------------+--------------+--------------+--------------|  
  |      30      |      31      |              |              |              |  
  |              |              |              |              |              |  
  |              |              |              |              |              |  
  |              |              |              |              |              |  
  |              |              |              |              |              |  
  |<=========Prototype=========+|              |              |              |  
  ----------------------------------------------------------------------------

Note that the durations of the activities in the project are multiples of 5. Thus, if work is done only on weekdays, all activities in the project last 0, 1, 2, or 3 weeks. The INTERVAL= option can also be used to set the units of duration to hours, minutes, seconds, years, months, quarters, or weeks. In this example, the data set WIDGWK is created from WIDGET to set the durations in weeks. PROC CPM is then invoked with INTERVAL=WEEK, and the resulting schedule is displayed in Output 2.6.3. Note that the float values are also expressed in units of weeks.

   data widgwk;
      set widget;
      weeks = days / 5;
      run;

   proc cpm data=widgwk date='2dec91'd interval=week;
      activity  task;
      successor succ1 succ2 succ3;
      duration  weeks;
      id task;
      run;

   title2 'INTERVAL=WEEK';
   proc print;
      id task;
      var e_: l_: t_float f_float;
      run;

Output 2.6.3: Changing Duration Units: INTERVAL=WEEK

Changing Duration Units

INTERVAL=WEEK

task	E_START	E_FINISH	L_START	L_FINISH	T_FLOAT	F_FLOAT
Approve Plan	02DEC91	08DEC91	02DEC91	08DEC91	0	0
Drawings	09DEC91	22DEC91	09DEC91	22DEC91	0	0
Anal. Market	09DEC91	15DEC91	20JAN92	26JAN92	6	0
Write Specs	09DEC91	15DEC91	16DEC91	22DEC91	1	1
Prototype	23DEC91	12JAN92	23DEC91	12JAN92	0	0
Mkt. Strat.	16DEC91	29DEC91	27JAN92	09FEB92	6	6
Materials	13JAN92	26JAN92	13JAN92	26JAN92	0	0
Facility	13JAN92	26JAN92	13JAN92	26JAN92	0	0
Init. Prod.	27JAN92	09FEB92	27JAN92	09FEB92	0	0
Evaluate	10FEB92	23FEB92	17FEB92	01MAR92	1	1
Test Market	10FEB92	01MAR92	10FEB92	01MAR92	0	0
Changes	02MAR92	08MAR92	02MAR92	08MAR92	0	0
Production	09MAR92	09MAR92	09MAR92	09MAR92	0	0
Marketing	10FEB92	10FEB92	09MAR92	09MAR92	4	4

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