SAS 9.4 Language Reference, 6th Edition

Creating Special Missing Values

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. For 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 Global Statements:

Reference.

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 $4. 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';

84 Chapter 5 • Missing Values