BIS524 Chapter 1

Two ways to solve these problems
Use of the INFORMAT statement
The FORMAT statement tells SAS, "print this variable this way". The INFORMAT statement tells SAS, "read this variable this way". If you add an INFORMAT statement before the INPUT statement all will be well.

DATA INFORMS;  
   INFORMAT LASTNAME $20. DOB MMDDYY8. GENDER $1.;  
   INPUT ID LASTNAME DOB HEIGHT WEIGHT GENDER AGE;  
   FORMAT DOB MMDDYY8.;  
DATALINES;

This INFORMAT statement says to the SAS compiler:

LASTNAME is a character variable that can hold up to 20 characters
DOB is a numeric variable whose input values are of the form mm/dd/yy.
(Note that you still need the FORMAT statement to tell SAS how to print DOB)
GENDER is a character variable that is only 1 character long