SAS - 표본 추출

SAS를 통한 표본 추출

sample.csv

임의추출

코드

FILENAME REFFILE 'C:\Users\\sample.csv';

PROC IMPORT DATAFILE=REFFILE
    DBMS=CSV
    OUT=WORK.population;
    GETNAMES=YES;
RUN;

proc surveyselect data=population method=srs n=200
    out=Work.sample;
run;

결과

The SAS System

The SURVEYSELECT Procedure

Selection Method	Simple Random Sampling

Input Data Set	POPULATION
Random Number Seed	137581001
Sample Size	200
Selection Probability	0.13708
Sampling Weight	7.295
Output Data Set	SAMPLE

표본 평균 계산

코드

proc surveymeans data=sample total=1459;
    var MSSubclass;
run;

결과

The SAS System

The SURVEYMEANS Procedure

Data Summary
Number of Observations	200

Statistics
Variable	N	Mean	Std Error of Mean	95% CL for Mean
MSSubClass	200	59.450000	2.648750	54.2267810	64.6732190

• 이 때, 표본 평균의 분산 추정량은 (N-n)/N * s^2/n 으로 계산된다. (유한 모집단이기 때문에 유한모집단 수정계수를 곱한다.)
• 모분산(sigma^2)을 아는 경우에는 (N-n)/(N-1) * sigma^2/n이다.

표본 비율의 추정

코드

data new;
    set sample;
    bin=(MSZoning='RL');
run;

proc surveymeans data=new total=1459;
    var bin;
run;

결과

The SAS System

The SURVEYMEANS Procedure

Data Summary
Number of Observations	200

Statistics
Variable	N	Mean	Std Error of Mean	95% CL for Mean
bin	200	0.760000	0.028124	0.70454146	0.81545854

층화 추출법

* LotShape라는 변수를 기준으로 층화추출한다. ;

proc sort data=population;
    by MasVnrType;
run;

proc freq data=population;
    tables MasVnrType;
run;

The SAS System

The FREQ Procedure

MasVnrType	Frequency	Percent	Cumulative Frequency	Cumulative Percent
BrkCmn	10	0.69	10	0.69
BrkFace	434	29.75	444	30.43
NA	16	1.10	460	31.53
None	878	60.18	1338	91.71
Stone	121	8.29	1459	100.00

proc surveyselect data=population method=srs n=(5,5,5,5,5)
    out=sample2;
    strata MasVnrType;
run;

The SAS System

The SURVEYSELECT Procedure

Selection Method	Simple Random Sampling
Strata Variable	MasVnrType

Input Data Set	POPULATION
Random Number Seed	132740001
Number of Strata	5
Total Sample Size	25
Output Data Set	SAMPLE2