Week 1

Question 1

What are some useful conventions for SAS code?

Answer 1

Case-insensitive
SAS keywords are usually in CAPS
All SAS statements end with a ;

Question 2

What is the DATA step?

Answer 2

A series of statements where a new sas data set can be created, manipulated or altered, new variables can be created or existing variables changed, labeled, mathematical functions can be used like to combine variables

Question 3

What are PROC steps?

Answer 3

Importing external data sheets
Summarizing data
Graph or chart data
Run statistics
Model data
Aggregate, sort, transpose or rearrange data

Question 4

What are some data set and variable name rules

Answer 4

One to 32 characters in length
Can’t start with a number
All data sets have two part names signify where it’s stored in the data sent name
I.e. WORK.databasename if temp
LIBNAME.database

Question 5

Embedded comments

Answer 5

Start with comment;
Or
/comment*/

Question 6

What are some common syntax errors?

Answer 6

Missing a RUN;
Omitting a;
Misspelled words
Leaving quotation marks on balanced or open
Using invalid options, keyword, terms

Question 7

Adding a dataset

Answer 7

DATA Name (of dataset);
INPUT V1 V2 V3 Vcharacter $;
DATALINES;
Enter your data in rows by variable
RUN;

Question 8

Rules on numeric data

Answer 8

Numbers as a raw value
Can have numbers 0–9, - , +, ., e
Missing data represented by a .
Cannot have $or commas
Cannot have leading zeros

Question 9

What are character data rules?

Answer 9

Anything goes
Missing data represented by a space
Can be framed in Sicle or double quotation marks

Question 10

Positional input with explicit formatting- numeric data

Answer 10

DATA filename;
INPUT @1 var1 3.0
This mean var1 goes in position 1, is 3 positions wide and no decimal points
Informat is #.#

Question 11

Positional input with explicit formatting - character data

Answer 11

INPUT @10 charvar3 $10
This means that variable three is in position 10 is and his charac
Informat or input format
$#.#

Question 12

What are the pros and cons of list input?

Answer 12

Pros: you do not need to know the column locations
Cons: not compact, must have spaces and can’t combine columns
Doesn’t handle missing data well sometimes doesn’t work with text files 

Question 13

Pros and cons of Column or position input

Answer 13

Pros: Reid data regardless of missing data position
Cons : need to be in proper column location, and need to know

Question 14

Pros and cons of explicit formatting

Answer 14

Pros: a lost for specific formats of variables
No surprises
Cons: requires knowledge of the data

Question 15

SAS libraries

Answer 15

SAS temporarily saves data sets to the Work library, it the default. File are name WORK.filename

You can store data set permanently by using the LIBNAME statement to specify path
Files named LIBNAME:filename

Question 16

Global options

Answer 16

Not tied to any data set
Remaining effect until they are changed
TITLE ‘xxxxx’;
OPTIONS ls =xx ps=x
-LS sets each line to be a maximum of X characters
-PS said the number of lines per output page at x lines maximum

Question 17

What command defines the names of variables?

Answer 17

INPUT
Basically names the columns
Character variables must be followed by a dollar sign

Question 18

How is missing data handled?

Answer 18

For numeric variables, missing values are denoted by .
Missing Character values denoted by a space

Question 19

What is column input?

Answer 19

All columns need to lineup and you specify the position
Add an index line
INPUT var1 1-3, var2 4-5, var3 7-10;

Question 20

Positional input with implicit formatting

Answer 20

Data must be in proper columns @# denotes the first position in a row for each data element

Question 21

Positional input with explicit formatting

Answer 21

• Data must be in the proper columns. @# denotes data position in row for
each variable.
• Denote informat
– Type format
• Numeric – format as #.#
• Character – format as $#. or $#.#
– Length is denoted by the first number in #.# or #. or $#.# or $
ie. INPUT @1 variable 3.0;
3 digits 0 decimals

Question 22

What is an informat?

Answer 22

Informats are used to specify the data type and field width of an input value
#.# for numeric variables
$#.# for character variables

Question 23

What does the double trailing @@ do?

Answer 23

Instructs sas to use multiple iterations of the data step to build multiple observations from each record of raw data.
XY@@ will repeat XY for multiple observations until it reaches the end of

Question 24

How do you create a permanent library?

Answer 24

LIBNAME dataset “c/:……”

Question 25

How do you save a temporary dataset in the WORK library into a permanent library?

Answer 25

DATA mydata.mydataset;
SET WORK.tempdataset;
RUN;
This is equivalent to this DATA step
DATA mydata.mydataset