The SHEWHART Procedure

specifies a plot character that identifies clipped points, as requested with the CLIPFACTOR= option. Specifying the CLIPCHAR= option is recommended when the CLIPFACTOR= option is used. The default character is an asterisk (*).

specifies the character used to form line segments that connect points on a chart. The default character is a plus (+) sign.

specifies the character used for reference lines requested by the HREF= and HREF2= options on line printer charts. The default is the vertical bar (|).

specifies a list of characters used to mark the points plotted on line printer charts when a symbol-variable is used. See Displaying Stratification in Levels of a Classification Variable.

Each character is associated with a level (unique value) of the symbol-variable and is used to mark points associated with that value. For example, consider the following statements:

proc shewhart;
   xrchart Gap*Shift=Machine / symbolchars='12345';
run;

Here the symbol-variable is Machine. The and R charts use a '1' to mark points associated with the first unique value of Machine, a '2' to mark points associated with the second unique value of Machine, and so on.

If the number of levels of the symbol-variable exceeds the number of characters, the last character listed is used for points associated with the additional values. Thus, in the preceding example, if there are six levels of Machine, points with the fifth and six values are indicated by '5'.

The default character-list is ABCDEFGHIJKLMNOPQRSTUVWXYZ*. Thus, the procedure uses 'A' for the first unique value of the symbol-variable, 'B' for the second unique value, and so on. An asterisk is used for points associated with the 27th and subsequent levels when the symbol-variable has more than 26 levels.

specifies the character for the line segments that connect any sequence of points for which a test for special causes (requested with the TESTS= or TESTS2= option) is positive. The default character is the number of the test (with values 1 to 8).

specifies the character used for reference lines requested by the VREF= and VREF2= options on line printer charts. The default is the hyphen (-).

specifies the character used to form the zone lines requested by the ZONES option. See the entry for the TESTS= option for a description of the zones. You do not need to specify the ZONES option if you specify the ZONECHAR= option. By default, the line between Zone A and Zone B uses the character 'B', and the line between Zone B and Zone C uses the character 'C'. Related options are TESTS=, TESTS2=, ZONES, and ZONES2.