请教SAS ADVANCE 题目

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马上要进行SAS 的高级考试了， 还有几道题目有点疑问，在此，想大家请教：希望指导！

When attempting to minimize memory usage, the

most efficient way to do group processing when


using the MEANS procedure is to use:



A.

the BY statement.




B.

GROUPBY with the NOTSORTED specification.



C.

the CLASS statement.




D.

multiple WHERE statements.



个人认为因该是选A，理由为， 但是看到有的答案选C，请指教！



A quick rule of thumb for the space


required to run PROC SORT is:



A.

two times the size of the SAS data set being sorted.




B.

three times the size of the SAS data set being sorted.




C.

four times the size of the SAS data set being sorted.




D.

five times the size of the SAS data set being sorted.




SAS pre guid 中有描述：
The SORT procedure is one technique that can be used to group or order data.
However, the SORT procedure can use a high volume of resources. When an
uncompressed data file is sorted using the SORT procedure, SAS requires enough space
in the data library for two copies of the data file, plus a workspace that is
approximately two to four times the size of the data file.

题中所言的the space
required to run 与 workspace 的含义是一致的吗？ 如果是的话，在SAS9.1
以后的本版中就应该是2倍的，如果值得是全部的话，就应该是4倍的？


The following SAS program is submitted:



data WORK.TEMP;

length A B 3 X;


infile RAWDATA;


input A B X;

run;



What is the length of variable A?




A.

3




B.

8




C.

WORK.TEMP is not created - X has an invalid length.



D.

Unknown.


通过程序验证，应该是C， 但是有参考答案为A，请指教


Given the following macro program:




%macro MAKEPGM(NEWNAME, SETNAME, PRINT);


data &NEWNAME;


set &SETNAME;


run;


%if &PRINT=YES %then %do;


proc print data=&NEWNAME.(obs=10);


run ;

%end;



%mend;




Which option would provide feedback in the


log about the parameter values passed into


this macro when invoked?




A.

MPRINT



B.

MDEBUG



C.

MLOGIC



D.

MPARAM


个人认为应该选A， 但有参考答案为C，请指导


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关键词：ADVANCE VANCE advan ance NCE 请教 题目 SAS ADVANCE

1.A quick rule of thumb for the space required to run PROC SORT is three times the size of the SAS data set being sorted.
这是我在网上查到的答案，与论坛上的答案不一样，你可以把整句话拷到Google里查一下，就会看到。
2.关于length A B 3 X; 这道题，WORK.TEMP is not created ，这是对的，但是，data set 的discribe 部分已经有了，所以，A的length 是3

140-2010: Dear Miss SASAnswers: A Guide to Sorting Your Data

中的描述是这样的：
If you want the sort to complete entirely in memory, a simple rule of thumb is four times the size of the data set. ....

2.关于length A B 3 X; 这道题，WORK.TEMP is not created ，这是对的，但是，data set 的discribe 部分已经有了，所以，A的length 是
用proc contents data=work.temp;run;
has the following output:
Alphabetic List of Variables and Attributes

                                  #    Variable    Type    Len

                                  1    A           Num       3
                                  2    B           Num       3
                                  3    X           Num       8

ding

Item 7 of 63
A quick rule of thumb for the space required to run PROC SORT is:
Beginning with SAS 9, the workspace required for an uncompressed data file
is approximately twice the size of the data file. The workspace can be
allocated in memory and/or on disk as a utility file, depending on the sort
utility and on the options chosen.
A.
two times the size of the SAS data set being sorted.

所以到底是什么呀？(′･_･`)

灵犀一指 发表于 2010-7-28 10:18
140-2010: Dear Miss SASAnswers: A Guide to Sorting Your Data

中的描述是这样的：

The multiplier 4 applies only to utility files used in releases prior to SAS 9, when PROC SORT needs to use disk space in order to sort the data. For in-memory sorting and sorting with SAS 9 and later, the multiplier is 2 or less.
Threaded processing takes advantage of multiple CPUs by executing multiple threads in parallel (parallel processing). Threaded procedures are completed in less real time than if each task were handled sequentially, although the CPU time is generally increased.  
When a threaded sort is used, the observations in the input data set are divided into equal temporary subsets, based on how many processors are allocated to the SORT procedure. Each subset is then sorted on a different processor. The sorted subsets are then interleaved to recreate the sorted version of the input data set.

sas adv prep