SAS 9.1.3 Language Reference: Concepts, Third Edition, Volumes 1 and 2
Definition
| special missing value |
is a type of numeric missing value that enables you to represent different categories of missing data by using the letters A-Z or an underscore . |
Tips
-
SAS accepts either uppercase or lowercase letters. Values are displayed and printed as uppercase.
-
If you do not begin a special numeric missing value with a period, SAS identifies it as a variable name . Therefore, to use a special numeric missing value in a SAS expression or assignment statement, you must begin the value with a period, followed by the letter or underscore, as in the following example:
x=.d;
-
When SAS prints a special missing value, it prints only the letter or underscore.
-
When data values contain characters in numeric fields that you want SAS to interpret as special missing values, use the MISSING statement to specify those characters . For further information, see the MISSING statement in SAS Language Reference: Dictionary .
Example
The following example uses data from a marketing research company. Five testers were hired to test five different products for ease of use and effectiveness. If a tester was absent, there is no rating to report, and the value is recorded with an X for "absent." If the tester was unable to test the product adequately, there is no rating, and the value is recorded with an I for "incomplete test." The following program reads the data and displays the resulting SAS data set. Note the special missing values in the first and third data lines:
data period_a; missing X I; input Id . Foodpr1 Foodpr2 Foodpr3 Coffeem1 Coffeem2; datalines; 1001 115 45 65 I 78 1002 86 27 55 72 86 1004 93 52 X 76 88 1015 73 35 43 112 108 1027 101 127 39 76 79 ; proc print data=period_a; title 'Results of Test Period A'; footnote1 'X indicates TESTER ABSENT'; footnote2 'I indicates TEST WAS INCOMPLETE'; run;
The following output is produced:
Output 6.1: Output with Multiple Missing Values
| |
Results of Test Period A Obs Id Foodpr1 Foodpr2 Foodpr3 Coffeem1 Coffeem2 1 1001 115 45 65 I 78 2 1002 86 27 55 72 86 3 1004 93 52 X 76 88 4 1015 73 35 43 112 108 5 1027 101 127 39 76 79 X indicates TESTER ABSENT I indicates TEST WAS INCOMPLETE
| |