Sample 24722: Simple random sample without replacement
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Select a random sample without replacement, where no observation can be chosen more than once.
Method 1 uses PROC SURVEYSELECT which is part of the SAS/STAT® software package. If you do not have SAS/STAT licensed, see Methods 2 and 3 which use Base SAS®.
These sample files and code examples are provided by SAS Institute Inc. "as is" without warranty of any kind, either express or implied, including but not limited to the implied warranties of merchantability and fitness for a particular purpose. Recipients acknowledge and agree that SAS Institute shall not be liable for any damages whatsoever arising out of their use of this material. In addition, SAS Institute will provide no support for the materials contained herein.
/* WORK.EASTHIGH is a data base of student grade point averages */
/* from East High School, Grades 9 through 12, 100 or more students per grade. */
data EastHigh;
format GPA 3.1;
do Grade=9 to 12;
do StudentID=1 to 100+int(201*ranuni(432098));
GPA=2.0 + (2.1*ranuni(34280));
output;
end;
end;
run;
/* Method 1: Using PROC SURVEYSELECT */
/* */
/* Use METHOD=SRS. N= is the number of observations to select. */
/* The sample is stored in the OUT= data set, SAMPLE1. */
proc surveyselect data=EastHigh method=srs n=15 out=sample1;
run;
title "Method 1: PROC SURVEYSELECT";
proc print data=sample1;
run;
/* Method 2: Using Base SAS */
/* Create a new variable X containing random numbers between 0 and 1 */
data random;
set EastHigh;
x=ranuni(1234);
run;
/* Sort on the random variable X */
proc sort data=random;
by x;
run;
/* Keep the first n observations. Since the data points are randomly */
/* sorted, these observations constitute a simple random sample. */
data sample2(drop=x);
set random (obs=15);
run;
title "Method 2: DATA step - with sort ";
proc print data=sample2;
run;
/* Method 3: Using SAS DATA Step with no sort required */
data sample3(drop=k n);
/* Initialize K to the number of sample obs needed and N to the */
/* total number of obs in the data set. */
retain k 15 n;
if _n_=1 then n=total;
set EastHigh nobs=total;
/* To randomly select the first observation for the sample, use the */
/* fact that each obs in the data set has an equal chance of being */
/* selected: k/n. If a random number between 0 and 1 is less than */
/* or equal to k/n, we select that the first obs for our sample */
/* and also adjust k and the number of obs needed to complete the */
/* sample. */
if ranuni(1230498) <= k/n then
do;
output;
k=k-1;
end;
/* At every iteration, adjust N, the number of obs left to */
/* sample from. */
n=n-1;
/* Once the desired number of sample points are taken, stop iterating */
if k=0 then stop;
run;
title "Method 3: DATA step, no sort ";
proc print data=sample3;
run;
These sample files and code examples are provided by SAS Institute Inc. "as is" without warranty of any kind, either express or implied, including but not limited to the implied warranties of merchantability and fitness for a particular purpose. Recipients acknowledge and agree that SAS Institute shall not be liable for any damages whatsoever arising out of their use of this material. In addition, SAS Institute will provide no support for the materials contained herein.
Method 1: PROC SURVEYSELECT 14:27 Thursday, November 4, 2004 41
Student
Obs GPA Grade ID
1 4.0 9 7
2 2.8 9 11
3 2.4 9 45
4 3.7 9 81
5 3.9 9 100
6 2.8 9 234
7 2.2 9 271
8 4.1 10 19
9 2.8 11 3
10 2.9 12 11
11 3.6 12 59
12 2.1 12 61
13 2.5 12 85
14 2.5 12 100
15 2.6 12 177
Method 2: DATA step - with sort 14:27 Thursday, November 4, 2004 42
Student
Obs GPA Grade ID
1 2.2 11 49
2 2.8 9 27
3 2.7 11 80
4 2.0 12 184
5 2.9 9 101
6 4.0 12 102
7 2.4 9 127
8 2.7 9 93
9 2.8 12 144
10 3.0 12 32
11 2.0 11 5
12 2.7 12 141
13 4.1 12 195
14 2.8 9 234
15 3.8 12 122
Method 3: DATA step, no sort 14:27 Thursday, November 4, 2004 43
Student
Obs GPA Grade ID
1 3.3 9 3
2 3.9 9 10
3 3.5 9 54
4 3.2 9 156
5 3.1 9 161
6 3.0 9 259
7 3.8 9 272
8 3.7 10 3
9 2.4 10 52
10 2.0 11 27
11 2.9 11 77
12 3.4 12 47
13 3.9 12 95
14 3.1 12 126
15 2.7 12 223
Select a random sample where no observation can be chosen more than once.
| Type: | Sample |
| Topic: | Analytics ==> Survey Sampling and Analysis SAS Reference ==> Procedures ==> SURVEYSELECT SAS Reference ==> DATA Step |
| Date Modified: | 2016-01-11 16:02:33 |
| Date Created: | 2004-09-30 14:09:07 |
Operating System and Release Information
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| Teradata on Linux | ||||
| z/OS | ||||
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| OpenVMS VAX | ||||
| Microsoft® Windows® for 64-Bit Itanium-based Systems | ||||
| Microsoft Windows Server 2003 Datacenter 64-bit Edition | ||||
| Microsoft Windows Server 2003 Enterprise 64-bit Edition | ||||
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| Microsoft® Windows® for x64 | ||||
| OS/2 | ||||
| Microsoft Windows 8 Enterprise 32-bit | ||||
| Microsoft Windows 8 Enterprise x64 | ||||
| Microsoft Windows 8 Pro 32-bit | ||||
| Microsoft Windows 8 Pro x64 | ||||
| Microsoft Windows 8.1 Enterprise 32-bit | ||||
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| Microsoft Windows 10 | ||||
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| Linux on Itanium | ||||
| OpenVMS Alpha | ||||
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| Solaris | ||||
| Solaris for x64 | ||||
| Tru64 UNIX | ||||
| SAS System | SAS/STAT | z/OS | ||
| z/OS 64-bit | ||||
| OpenVMS VAX | ||||
| Microsoft® Windows® for 64-Bit Itanium-based Systems | ||||
| Microsoft Windows Server 2003 Datacenter 64-bit Edition | ||||
| Microsoft Windows Server 2003 Enterprise 64-bit Edition | ||||
| Microsoft Windows XP 64-bit Edition | ||||
| Microsoft® Windows® for x64 | ||||
| OS/2 | ||||
| Microsoft Windows 8 Enterprise 32-bit | ||||
| Microsoft Windows 8 Enterprise x64 | ||||
| Microsoft Windows 8 Pro 32-bit | ||||
| Microsoft Windows 8 Pro x64 | ||||
| Microsoft Windows 8.1 Enterprise 32-bit | ||||
| Microsoft Windows 8.1 Enterprise x64 | ||||
| Microsoft Windows 8.1 Pro | ||||
| Microsoft Windows 8.1 Pro 32-bit | ||||
| Microsoft Windows 10 | ||||
| Microsoft Windows 95/98 | ||||
| Microsoft Windows 2000 Advanced Server | ||||
| Microsoft Windows 2000 Datacenter Server | ||||
| Microsoft Windows 2000 Server | ||||
| Microsoft Windows 2000 Professional | ||||
| Microsoft Windows NT Workstation | ||||
| Microsoft Windows Server 2003 Datacenter Edition | ||||
| Microsoft Windows Server 2003 Enterprise Edition | ||||
| Microsoft Windows Server 2003 Standard Edition | ||||
| Microsoft Windows Server 2003 for x64 | ||||
| Microsoft Windows Server 2008 | ||||
| Microsoft Windows Server 2008 R2 | ||||
| Microsoft Windows Server 2008 for x64 | ||||
| Microsoft Windows Server 2012 Datacenter | ||||
| Microsoft Windows Server 2012 R2 Datacenter | ||||
| Microsoft Windows Server 2012 R2 Std | ||||
| Microsoft Windows Server 2012 Std | ||||
| Microsoft Windows XP Professional | ||||
| Windows 7 Enterprise 32 bit | ||||
| Windows 7 Enterprise x64 | ||||
| Windows 7 Home Premium 32 bit | ||||
| Windows 7 Home Premium x64 | ||||
| Windows 7 Professional 32 bit | ||||
| Windows 7 Professional x64 | ||||
| Windows 7 Ultimate 32 bit | ||||
| Windows 7 Ultimate x64 | ||||
| Windows Millennium Edition (Me) | ||||
| Windows Vista | ||||
| Windows Vista for x64 | ||||
| 64-bit Enabled AIX | ||||
| 64-bit Enabled HP-UX | ||||
| 64-bit Enabled Solaris | ||||
| ABI+ for Intel Architecture | ||||
| AIX | ||||
| HP-UX | ||||
| HP-UX IPF | ||||
| IRIX | ||||
| Linux | ||||
| Linux for x64 | ||||
| Linux on Itanium | ||||
| OpenVMS Alpha | ||||
| OpenVMS on HP Integrity | ||||
| Solaris | ||||
| Solaris for x64 | ||||
| Tru64 UNIX | ||||