The GANTT Procedure

Page Format

The GANTT procedure divides the observations (activities) into a number of subgroups of approximately equal numbers. The size of each group is determined by the PAGESIZE system option. Similarly, the time axis is divided into a number of approximately equal divisions depending on the LINESIZE system option.

If the FILL option is specified, however, each page is filled as completely as possible before plotting on a new page. If both axes are split, the pages are ordered with the chart for each group of activities being plotted completely (the time axis occupying several consecutive pages, if needed) before proceeding to the next group.

If a BY statement is used, each BY group is formatted separately.

Two options that control the format of the chart are the MININTERVAL= and SCALE= options. The value for the MININTERVAL= option, denoted by mininterval, is the smallest time interval unit to be identified on the chart. The value for the SCALE= option, denoted by scale, is the number of columns to be used to denote one unit of mininterval. For example, if MININTERVAL=MONTH and SCALE=10, the chart is formatted so that 10 columns denote the period of one month. The first of these 10 columns denotes the start of the month and the last denotes the end, with each column representing approximately three days. Further, the INCREMENT= option can be used to control the labeling. In this example, if INCREMENT=2, then the time axis would have labels for alternate months.

Specifying the MININTERVAL= Option

The value specified for the MININTERVAL= option is the smallest time interval unit to be identified on the chart. If the time values being plotted are SAS date values, the valid values for mininterval are DAY, WEEK, MONTH, QTR, or YEAR. If the values are SAS datetime values, valid values for mininterval are DTSECOND, DTMINUTE, DTHOUR, DTDAY, DTWEEK, DTMONTH, DTQTR, or DTYEAR. If they are SAS time values, then valid values are SECOND, MINUTE, or HOUR.

Note: If the times being plotted are SAS datetime values and mininterval is either DTSECOND, DTMINUTE, or DTHOUR, the output generated could run into several thousands of pages. Therefore, be careful when choosing a value for mininterval.

Table 6.21 shows the default values of mininterval corresponding to different formats of the times being plotted on the chart.

Table 6.21: Default Values of the MININTERVAL= Option

Labeling on the Time Axis

If the variables being plotted in the chart are unformatted numeric values, the time axis is labeled by the corresponding numbers in increments specified by the INCREMENT= option. However, if the variables have date, datetime, or time formats, then the time axis is labeled with two or three lines. Each line is determined by the value of mininterval, which in turn is determined by the format of the plotted times (see Table 6.21). Table 6.22 illustrates the format of the label corresponding to different values of mininterval.

Table 6.22: Label Format Corresponding to MININTERVAL= Value