The CPM Procedure

BASELINE Statement

BASELINE / options ;

The BASELINE statement enables you to save a specific schedule as a baseline or target schedule and compare another schedule, such as an updated schedule or resource constrained schedule, against it. The schedule that is to be saved as a baseline can be specified either by explicitly identifying two numeric variables in the input data set as the B_START and B_FINISH variables, or by indicating the particular schedule (EARLY, LATE, ACTUAL, or RESOURCE constrained schedule) that is to be used to set the B_START and B_FINISH variables. The second method of setting the schedule is useful when you want to set the baseline schedule on the basis of the current invocation of PROC CPM.

Note that the BASELINE statement needs to be specified in order for the baseline start and finish times to be copied to the Schedule data set. Just including the B_START and B_FINISH variables in the Activity data set does not initiate baseline processing.

The following options can be specified in the BASELINE statement after a slash (/).

B_FINISH= variable BF=variable

specifies the numeric-valued variable in the Activity data set that sets B_FINISH.

B_START= variable BS=variable

specifies the numeric-valued variable in the Activity data set that sets B_START.

COMPARE=schedule

compares a specific schedule (EARLY, LATE, RESOURCE or ACTUAL) in the Activity data set with the baseline schedule. The COMPARE option is valid only if the input data set already has a B_START and a B_FINISH variable or if the SET= option is also specified. In other words, the COMPARE option is valid only if there is a baseline schedule to compare with. The comparison is specified in two variables in the Schedule data set, S_VAR and F_VAR, which have the following definition:

            S_VAR = Compare Start - B_START;
            F_VAR = Compare Finish - B_FINISH;

where Compare Start and Compare Finish refer to the start and finish times corresponding to the schedule that is used as a comparison.

The values of the variables S_VAR and F_VAR are calculated in units of the INTERVAL= parameter, taking into account the calendar defined for the activity.

SET=schedule

specifies which of the four schedules (EARLY, LATE, RESOURCE, or ACTUAL) to set the baseline schedule equal to. The SET= option causes the addition of two new variables in the Schedule data set; these are the B_START and B_FINISH variables. The procedure sets B_START and B_FINISH equal to the start and finish times corresponding to the EARLY, LATE, ACTUAL, or RESOURCE schedules. If the Activity data set already has a B_START and B_FINISH variable, it is overwritten by the SET= option and a warning is displayed. The value RESOURCE is valid only if resource-constrained scheduling is being performed, and the value ACTUAL is valid only if the ACTUAL statement is present.

Note: The values ACTUAL, RESOURCE, and so on cause the B_START and B_FINISH values to be set to the computed values of A_START, S_START, …, and so on. They cannot be used to set the B_START and B_FINISH values to be equal to, say, A_START and A_FINISH or S_START and S_FINISH, if these variables are present in the Activity data set; to do that you must use B_START=A_START, B_FINISH=A_FINISH, and so on.

UPDATE=schedule

specifies the name of the schedule (EARLY, LATE, ACTUAL, or RESOURCE) that can be used to update the B_START and B_FINISH variables. This sets B_START and B_FINISH on the basis of the specified schedules only when the values of the baseline variables are missing in the Activity data set. The UPDATE option is valid only if the Activity data set already has B_START and B_FINISH. Note that if both the UPDATE= and SET= options are specified, the SET= specification is used.