Date: Wed, 18 Jun 2003 08:38:52 -0400
Reply-To: Peter Flom <flom@NDRI.ORG>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: Peter Flom <flom@NDRI.ORG>
Subject: Re: Need answers to SAS certification questions
Content-Type: text/plain; charset=US-ASCII
Indeed, I got my PhD in Psychometrics, which involves construction of
such tests. It is, as Phil states, a major endeavor. Plus, after a
test is constructed, it needs a sensible scoring method. I wonder
whether they are using classical test theory, or item response theory,
or what?
Now, I'm lucky. I don't need to pass SAS Certification. And I don't
know enough about a lot of SAS to have realized how poor these questions
are. But clearly SOME people DO need to be SAS certified. If the test
is really that bad (and I will take your collective word for it) then
SAS (or whoever devised the test) might be in real trouble.
Peter
>>> Phil Rack <philrack@MINEQUEST.COM> 06/17/03 09:06PM >>>
Sig, Jack and others...
Answering those questions would have been a WAG for me! It makes you
wonder
if/how they field tested it and whether they came up with any reliable
or valid items. I would love to see the Institute publish a paper
that
addresses such issues. Right out of college, I worked for an
educational
testing
company and it was a major task to do such things properly. We spent
months
a
lot of time working out our sample before field testing and spent
months
writing
the documentation of the supporting statistics for each and every
question.
-----Original Message-----
From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU]On Behalf Of
Sigurd Hermansen
Sent: Tuesday, June 17, 2003 4:52 PM
To: SAS-L@LISTSERV.UGA.EDU
Subject: Re: Need answers to SAS certification questions
These questions remind me of a SNL skit with Steve Martin as the host
of a
TV quiz show. The contestants (including, supposedly, Jeanne
Kirkpatrick)
had to respond to questions about American history with answers
selected
from the results of a poll of high school students. Knowledgeable
contestants had no chance of winning.
Let's see how this works:
Question 1: 2,3,5, probably in that order. 3 and 5 are not valid
options;
Question 2: none of the choices. The ps= system option (must be what
they
mean by 'global') has a maximum of 32,767 lines or 1,024 pages. Could
they
mean OPTIONS IGETNOBREAKS?
Question 3: The condition IF _TYPE_='11110101'B would make the
question
merely obscure, arcane, and archaic. Stating the condition as IF
_TYPE_='....0.0.'B makes the question just plain peculiar. I could
probably
guess the right answer, but I have no idea how to evaluate the
condition as
written.
Question 4: I would go with 1; nonetheless, in a computing environment
as
complex as SAS, programmers don't really know or care.
Question 5: Suppose the supreme examiner is selecting correct answers
at
random. The odds on favorite for the correct answer to this question
would
be 2. Or 4. (Sure that you haven't copied this question incorrectly?)
Question 6: This question actually makes sense to me. I have not
checked the
syntax, but (except for (... the label ... then prints the label)
Choice 2
looks good.
Question 7: I like to go with the 'None of the above' choices. Test
developers tend to believe that test takers will fall for at least one
of
the other choices.
I've checked my answers against those provided by Jack Hamilton, a
more
serious scholar of SASology, and I agree with his comments on the
ambiguities in the questions. Are we really looking at official and
correct
questions on the SAS certification exam? That's a scary thought.
Sig
-----Original Message-----
From: Quanda Garland [mailto:quandagarland@YAHOO.COM]
Sent: Thursday, June 12, 2003 5:52 PM
To: SAS-L@LISTSERV.UGA.EDU
Subject: Need answers to SAS certification questions
Hello,
Could some body help me to find the correct answers for the following
question. Some are vague to me.
Which option below has NO effect on the number of observations selected
in a
DATA step?
Choice 1
OBS=0
Choice 2
ERRORS=0
Choice 3
ABORTABEND
Choice 4
ERRORABEND
Choice 5
ABORT
Which global OPTION below can be used to prevent page breaks when using
PROC
PRINTTO?
Choice 1
MPRINT
Choice 2
NOTITLES
Choice 3
NOBREAKS
Choice 4
PAGESIZE=
Choice 5
LS=
IF _TYPE_='....0.0.'B;? You are using a DATA step to post-process an
output
data set from a PROC MEANS that had eight class variables. What is the
purpose of the statement above?
Choice 1
It selects only the observations subgrouped by the 5th or 7th class
variables.
Choice 2
It selects only the observations subgrouped by the 4th or 6th class
variables.
Choice 3
It selects every observation except those subgrouped by the 4th and
6th
class variables.
Choice 4
It selects every observation except those subgroups involving the 5th
and
7th class variables.
Choice 5
It reformats the numeric variables into a hexadecimal format.
When you submit a DATA step, what is the first action taken by the SAS
System?
Choice 1
The system will compile SAS statements.
Choice 2
The system will begin with a DATA statement.
Choice 3
The system will set variables to missing.
Choice 4
The system will read an input record.
Choice 5
The system will create an input buffer.
Which statements below are used in a program that writes customized
reports
using "PUT" statements?
Choice 1
proc printto;
Choice 2
data _null_;
file print;
Choice 3
proc tabulate;
Choice 4
data _null_;
put _all_;
Choice 5
proc sql;
proc format;
value x (fuzz=.3) 1='one' 2='two' 3='three';
What is the purpose of the FUZZ option in the sample code above?
Choice 1
It specifies a width of the decimal value - in this case 3 decimal
places.
Choice 2
It indicates that if a variable falls within .3 of the value specified
in
the value statement, the corresponding label is used to print the
value.
Choice 3
It prints the label defined in the value if the variable value contains
a
.3.
Choice 4
It multiplies the value of the variable times .3, and if the result
equals
the label (a certain number as defined in the DATA step), then prints
the
label.
Choice 5
It divides the value of the variable by .3, and if the result equals
the
label (a certain number as defined in the DATA step), then prints the
label.
Which of the following is true of compressed data sets?
Choice 1
Storage requirements are always decreased.
Choice 2
CPU time required to prepare observations for input/output operations
is
decreased.
Choice 3
The FIRSTOBS= and OBS= data set options can be used.
Choice 4
The POINT= set option in the set statement can be used.
Choice 5
None of the above are true.
You need to write out a comma-delimited flat file for import into MS
Excel.
Given that all values in your data set are positive and below 100000,
what
FORMAT used to write to the file would cause problems during the
import?
Choice 1
DOLLAR7.
Choice 2
5.
Choice 3
DOLLAR7.2
Choice 4
$5
Choice 5
7.2
TIA,
Garland
Shane Hornibrook <shane_sasl_nospam1@ShaneHornibrook.com> wrote:
Garland,
You've gotten great responses from Sigurd Hermansen, David L. Cassell,
and
JP. I have a bit to add to their code. If you run some of the example
code
using "select * from" and joining varibles with the same name you will
notice WARNINGs in the log.
Using David L. Cassell's code as the base;
proc sql noprint;
create table dm as
select * from ds1 as a left join ds2 as b
on a.subjid=b.subjid and a.lbtst=b.lbtst;
quit;
If you run the code you will get warnings similar to
"WARNING: Variable subjid already exists on file WORK.DM."
"WARNING: Variable lbtst already exists on file WORK.DM."
You can avoid these warnings by adding a RENAME to one set of
variables,
and dropping the renamed variables on the created table. It is not a
required part of the SQL join, but it keeps your log file uncluttered.
The modified code looks like;
proc sql noprint;
create table dm(drop=subjid_temp lbtst_temp) as
select * from ds1 as a left join ds2
(rename=(subjid=subjid_temp lbtst=lbtst_temp))
as b
on a.subjid=b.subjid_temp and a.lbtst=b.lbtst_temp;
quit;
run;
It looks a little 'crufty', but it works, and may save you a bit of
time
when reviewing your log files. On the downside, your code will run
perhaps
30% slower than the non-renamed-variable SQL. This performance hit is
in
addition to the overhead of using PROC SQL vs the comparable datastep.
This may become an issue if you are joining more than 500,000 records
(As
written and tested on an IBM AIX RS/6000 SAS v8 .... your mileage may
vary).
In this case it seems faster (in all regards) to code and run the
equivalent data step.
--Shane
Shane Hornibrook
Mobile: (902)441-4158
shane_sasl_nospam1@shanehornibrook.com
http://www.shanehornibrook.com/
On Fri, 24 Jan 2003, Garland wrote:
> Hi,
>
> I have the following program. Can anybody give me the PROC SQL query
> for the following datastep. I am learing proc sql just started to
> convert the previously written programs to proc sql as an exercise.
>
> Thanks in advance,
> Garland
>
> Data ds1;
> Input subjid lbtst$ lowhigh $;
> Datalines;
> 1001 ALBUMIN NH
> 1001 BUN NL
> 1002 CALCIUM NH
> 1002 BUN NL
> 1002 LDH NH
> ;
>
> Data ds2;
> Input subjid studydy lbtst$ ;
> Datalines;
> 1001 0 ALBUMIN
> 1001 1 ALBUMIN
> 1001 7 ALBUMIN
> 1001 14 ALBUMIN
> 1001 0 BUN
> 1001 1 BUN
> 1001 1 URIC_ACID
> 1001 2 GLUCOSE
> 1002 1 CALCIUM
> 1002 1 BUN
> 1002 0 LDH
> 1003 2 SODIUM
> 1003 2 LDH
> ;
>
> run;
>
> proc sort data=ds1;
> by subjid lbtst;
> run;
>
> proc sort data=ds2;
> by subjid lbtst;
> run;
>
> data dm;
> merge ds1(in=aa) ds2;
> by subjid lbtst;
> if aa;
> run;
>
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