Program c correctly deletes the observation in which the value of Finish is oak and the value of Price is less than 200. It also creates TotalPrice by summing the variable Price down observations, and then drops Price by using the DROP statement in the DATA step.

Logical comparisons that are enclosed in parentheses are evaluated as true or false before they are compared to other expressions. In the example, the AND comparison within the nested parentheses is evaluated before being compared to the OR comparison.

You must enclose character values in quotation marks, and you must specify them in the same case in which they appear in the data set. The value OK is not identical to Ok, so the value of Count is not changed by the IF-THEN statement.

The length of a variable is determined by its first reference in the DATA step. When creating a new character variable, SAS allocates as many bytes of storage space as there are characters in the reference to that variable. The first reference to a new variable can also be made with a LENGTH statement or an assignment statement.

You can write multiple ELSE statements to specify a series of mutually exclusive conditions. The ELSE statement must immediately follow the IF-THEN statement in your program. An ELSE statement executes only if the previous IF-THEN/ELSE statement is false.

The length of a new variable is determined by the first reference in the DATA step, not by data values. In this case, the length of Type is determined by the value Fixed. The LENGTH statement is in the wrong place; it must occur before any other reference to the variable in the DATA step. You can run PROC CONTENTS on the data set to see the length of each variable.

To select variables, you can use a DROP or KEEP statement in any DATA step. You can also use the DROP= or KEEP= data set options following a data set name in any DATA or PROC step. However, you cannot use DROP or KEEP statements in PROC steps.

The variables Age, Weight, and Group are specified using the KEEP= option in the SET statement. When Cert.Fitness is being read, Age, Weight, and Group are the variables that create Work.Cardiac. The variables Age and Group are specified in the DROP= option in the DATA statement. Age and Group are dropped from Work.Cardiac.

You specify the data set to be created in the DATA statement. The DROP= data set option prevents variables from being written to the data set. Because you use the variable OrdrTime when processing your data, you cannot drop OrdrTime in the SET statement. If you use the KEEP= option in the SET statement, then you must list OrdrTime as one of the variables to be kept.