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= data set option in the DATA statement.

The PROC PRINT output displays the label Total Amount Loaned for the variable Amount and formats this variable using the COMMA10. format. Temporary labels or formats that are assigned in a PROC step override permanent labels or formats that are assigned in a 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.

The sum statement adds the result of the expression that is on the right side of the plus sign to the numeric variable that is on the left side. The new value is then retained for subsequent observations. The sum statement ignores the missing value, so the value of Count in the fourth observation would be 10+20+0+40, or 70.

The RETAIN statement assigns an initial value of 100 to the variable Count, so the value of Count in the third observation would be 100+10+20+0, or 130.

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.

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.