Sas tutorial 0308

SAS tutorial 0308:Correlation

PROC CORR

BY, VAR, WEIGHTFREQ

IDPARTIAL

WITH

– 指定各觀察值的出現次數。– 指定變項用以描述資料。– 指定要以那個變項為基準計算淨

相關。

– 指定變項，和用 VAR 指定的變項作相關。

data Fitness; input Age Weight Oxygen RunTime @@; datalines; 44 89.47 44.609 11.37 40 75.07 45.313 10.07 44 85.84 54.297 8.65 42 68.15 59.571 8.17 38 89.02 49.874 . 47 77.45 44.811 11.63 40 75.98 45.681 11.95 43 81.19 49.091 10.85 44 81.42 39.442 13.08 38 81.87 60.055 8.63

......;

ods graphics on;proc corr data=Fitness plots=matrix(histogram);run;ods graphics off;

proc corr; var x1 x2; with y1 y2 y3; run;

data Setosa;input SepalLength SepalWidth PetalLength PetalWidth @@;label sepallength='Sepal Length in mm.'

sepalwidth='Sepal Width in mm.'petallength='Petal Length in mm.'petalwidth='Petal Width in mm.';

datalines; 50 33 14 02 46 34 14 03 46 36 . 02 51 33 17 05 55 35 13 02 48 31 16 02 52 34 14 02 49 36 14 01 44 32 13 02 48 30 14 01 45 23 13 03 57 38 17 03 51 38 15 03 54 34 17 02 51 37 15 04

......;

ods graphics on;title 'Fisher (1936) Iris Setosa Data';proc corr data=Setosa sscp cov plots=scatter;var sepallength sepalwidth;with petallength petalwidth;run;ods graphics off;

PROC CORR statements-1

PROC CORR statements-2

Check

Display scatter plots.Compute

Pearson’s correlation coefficient.Fisher’s z transformation.Kendall’s tau.Spearman rank-order correlation.Partial correlation.Cronbach’s alpha.

Handle missing values.Variance/covariance matrix.

Review

• PROC FREQ• PROC STANDARD

Chi-square distribution

χ❑2

(𝑘)=∑𝑖=1

𝑘

𝑍 𝑖❑2

Example

• Q: 男性跟女性同意婚前性行為的傾向有差別嗎？

Agree No opinion Disagree TotalMale 279 73 225 577Female 175 47 201 423Total 454 120 426 1000

Expected Agree No opinion DisagreeMale 261.96 69.24 245.80Female 192.04 50.76 180.20

𝐸=1000∗5771000

∗4541000

Compare with a critical value

Why?

Why?Why?

SAS Code

DATA ex1;DO i=1 to 2; DO j=1 to 3; INPUT x @@; OUTPUT; END;END;DATALINES;279 73 225175 47 201;

PROC PRINT DATA=ex1;

PROC FREQ DATA=ex1;TABLES i*j/CHISQ;WEIGHT x;RUN;

Results

這些指標各代表什麼意義？

想一下• Q1: 為什麼 Fisher’s exact test 是 “ Exact” ？• Q2: Binomial counts 可以跑 Chi-square test 嗎？• Q3: 找一組 2*2 的資料，比較以下兩者 output 的差別。

PROC FREQ DATA=AAA;EXACT FISHER;...;

PROC FREQ DATA=AAA;EXACT CHISQ; ...;

怎麼算出來的 ?

PROC STANDARD

• 把分數調成平均 80 ，標準差 10 的常態分配。

SAS codePROC IMPORT OUT=EX2 DATAFILE="C:\Users\user\Desktop\QUIZ.txt" DBMS=dlm REPLACE;GETNAMES=YES;DELIMITER='09'x;

PROC STANDARD DATA=ex2 MEAN=80 STD=10 OUT=ex3PRINT;

VAR Score;

PROC PRINT DATA= ex2;PROC PRINT DATA= ex3;RUN;

從文字檔讀資料

標準化

Results

Technology

Sas tutorial 0308