bas 150 lesson 5 lecture

BAS 150Lesson 5: Conditional Statements and Iterative Processing

• Utilize conditional statements to analyze data

• Apply iterative processing to SAS programs

• Organize SAS code to run efficient SAS programs

This Lesson’s Learning Objectives

Conditional Statements

IF <condition> THEN <X>;

ELSE <Y>;

If Score >= 70 Then Grade = 'Passing Grade';

Else Grade = 'Failing Grade';

Using If, Then, Else

Student Score GradeJane 75 Passing Grade

Dave 56 Failing Grade

Jack 90 Passing Grade

Sue 68 Failing Grade

Assignment statementUsed to create new variables

IF <condition> THEN <X>;

ELSE IF <condition2> THEN <Y>;

ELSE <Z>;

If Score >= 70 Then Grade = 'Passing Grade';

Else If 60 <= Score <= 69 Then Grade = 'Incomplete';

Else Grade = 'Failing Grade';

Using If, Then, Else, Else If (1 of 2)

Student Score Grade

Jane 75 Passing GradeDave 56 Failing GradeJack 90 Passing GradeSue 68 Incomplete

Use when more than 2 choices exist in a conditional world…

Used to create new variables

When using ELSE IF:

o Processes IF-THEN conditions until first true

statement is met, then it moves on to the next

observation

oOnce a condition is met, the observation is not

reevaluated

Using If, Then, Else, Else If (2 of 2)

If Score >= 90 Then Grade = 'A';

If Score >= 80 Then Grade = 'B';

If Score >= 70 Then Grade = 'C';

If Score >= 60 Then Grade = 'D';

If Score < 60 Then Grade = 'F';

Efficient Coding … If, Then, Else (1 of 2)

Student Score GradeJane 75 D

Dave 56 F

Jack 90 D

Sue 68 D

Q: Why is this happening?

A: Most recent “If Then” Statement overrides prior

one.

If Score >= 90 Then Grade = 'A';

ELSE If Score >= 80 Then Grade = 'B';

ELSE If Score >= 70 Then Grade = 'C';

ELSE If Score >= 60 Then Grade = 'D';

ELSE If Score < 60 Then Grade = 'F';

Efficient Coding…If, Then, Else (2 of 2)

Student Score GradeJane 75 C

Dave 56 F

Jack 90 A

Sue 68 D

More efficient and accurate.

Arithmetic Symbol Example

Addition + Xplus = 4+2;Subtraction – Xminus = 4-2;Multiplication * Xmult = 4*2;Division / Xdiv = 4/2;Exponents ** Xexp = 4**2;Negative numbers – Xneg = -2;

Arithmetic Operators

Logical comparison Mnemonic Symbol

Equal to EQ =

Not equal to NE ^= or ~=

Less than LT <

Less than or equal to LE <=

Greater than GT >

Greater than or equal to GE >=

Equal to one in a list IN

Not equal to any in a list NOT IN

Comparison Operators

Note: <> also used for not equal to, but only in PROC SQL

Boolean Operators

And

Or

Not

Logical Operators

1. Arithmetic operators

2. Comparison operators (<, >, =, LIKE, etc.)

3. Logical operators a. NOTb. ANDc. OR

Use parentheses to control the order of operations

Order of Operations

Logical conditions can be as complicated as

you need them to be

o Just make sure your order of operations is correct

If, Then, Else (cont.)

Iterative Processing

DO Groups (1 of 5)

IF <condition> THEN DO;

<X>; <Y>; <Z>;

END;

If Score >= 90 Then Do;Grade = 'A'; Pass_Fail = 'Pass';

End;

DO Groups (2 of 5)

DO Groups (3 of 5)

DO Groups (4 of 5)

DO Groups (5 of 5)

Sum Statement (1 of 5)

Variable + expression

Running totals or counters

Sum Statement (2 of 5)

Sum Statement (3 of 5)

Sum Statement (4 of 5)

Sum Statement (5 of 5)

Iterative DO Loop (1 of 7) $100

3.75%

Iterative DO Loop (2 of 7) $100

3.75%

Iterative DO Loop (3 of 7) $100

3.75%

Iterative DO Loop (4 of 7)

Iterative DO Loop (5 of 7)• $100• 3.75%

Iterative DO Loop (6 of 7)

Iterative DO Loop (7 of 7)

DO Until

DO While

DO Loop Error

A Review of DODO Group Processin

g

Designates a group of

statements to be executed

as a unit.

Iterative DO Loop

Executes statements repetitively

based on the value of an

index variable.

DO Until

Executes a DO Loop until a condition is

true

Checks the condition after the iteration of each DO Loop

Do While

Executes a DO Loop until a condition is

false

Checks the condition before the iteration of

each DO Loop

• Utilize conditional statements to analyze data

• Apply iterative processing to SAS programs

• Organize SAS code to run efficient SAS programs

Summary - Learning Objectives

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