Date: Tue, 12 May 1998 13:55:46 -0700
Reply-To: Patricia K Flickner <Patricia.K.Flickner@AEXP.COM>
Sender: "SAS(r) Discussion" <SAS-L@UGA.CC.UGA.EDU>
From: Patricia K Flickner <Patricia.K.Flickner@AEXP.COM>
Subject: SAS questions
There were some people who couldn't read the attached SAS questions, so I
redid them. Pat
SAS Questions:
Base SAS
A. Creating a SAS set:
1. What SAS statement would you code to read in an external
raw data file to SAS?
2. How do you read in the variables that you need on that
file?
3. Are you familiar with special input delimiters?If so, how would you
let SAS know what those were?
4. If you're reading in a variable length file with fixed
input, how
would you prevent SAS from reading the next record if the
last variable
didn't exist on a record?
5. What is the difference between an informat and a format?
6. Name three informats or formats.
7. Name three SAS functions that you have used, if any?
8. How would you code the criteria to restrict the output to
be produced?
There are a couple of ways to do this.
9. Have you ever used a trailing @? If so, how did you use
it?
10. Have you ever coded a select? If so:
a. When would a select be superior to an if statement?
b. Code a select.
B. Creating external raw data files
1. What statement do you code to tell SAS that it is to write
to an
external file?
2. What statement to you code to write the record to the
file?
3. If you're reading in an external file to produce the
external file and
you need to produce the file exactly, do you know the shortcut to write
that record without coding every single variable on the
record? If so,
describe.
C. Misc.
1. If you're not wanting any SAS output from a data step, how
would you
code the data statement to prevent SAS from producing a set?
2. What is the one statement to set the criteria of data that
can be
coded in any SAS step?
3. Have you ever linked SAS code? If so, describe the link
and any
required statements used to either process the code or the step itself.
4. How would you include common code to be processed along
with your SAS
statements?
5. Code a do loop.
6. You are looking for specific data contained somewhere in a
character
string of 150 bytes. Which function is the best to locate
that data:
scan, index, or indexc? Why?
7. If you have a set that contains 100 variables, but you
need only five
of those, what is the code to force SAS to use only those variable?
8. Where is it most efficient to use the statement? Can this
statement
be used anywhere else besides the data step? Where?
9. Have you ever merged two or more SAS sets?
a. Code a merge statement.
b. Code a merge that will keep only the observations that have matches
from both sets.
c. Code a merge that will move the matches of both to
one set, the
non-match of the first set to a second set, and the
non-match of
the second to a third set.
D. Using SAS sets
1. The data contains variables State, District and County as
the primary
variables, along with several numeric variables.
2. Proc Sort
a. Code a Proc Sort.
b. How would you delete duplicate observations?
(Note: for
those of you unfamiliar with the slight problem
with this
process, unless you do a sort on every variable in
an observation,
duplicate obs that are not back-to-back will not be
deleted
simply because this de-duping process compares the current obs
with the previous obs.)
c. How would you delete observations with duplicate
keys?
(No problems with this one.)
d. How would you keep SAS from overlaying the a SAS
set with its
sorted version?
3. Proc Freq
a. Code the tables statement for a single-level (most
common) frequency.
b. Code the tables statement to produce a multi-level
frequency.
1) Name the option to produce a frequency
listing rather than a
table.
c. Produce output from the frequency.
d. Restrict the printing of the table.
4. Proc Means
a. Code a Proc Means that show both summed and meaned
output of the data.
b. Code the option that will allow Means to include
missing numeric
data to be included in the report.
c. Code the Means to produce output to be used later.
C. Macro Language
1. Describe how you would create a macrovariable. There are
at least three.
2. If you use a symput in a data step, can you use the
macrovar right away?
Explain.
3. What do you code to create a macro? End one?
4. Describe how you would pass data to a macro.
5. You have variables 1 thru 5 that need to be processed
identically; how
would you simplify that processing with a macro?
6. How would you code a macro statement to produce information on the SAS
log?
This statement can be coded anywhere.
7. How do you add a number to a macrovariable?
8. If you need the value of a variable rather than the
variable itself, what
would you use to load the value to a macrovariable?
9. Can you execute a macro within a macro? Describe.
10. Can you create another macro within the macro you are
creating?
11. If so, how would SAS know where the current macro ended
and the new one
began?
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