Sas tutorial glm2

SAS tutorial: GLM (2)

Repeated measures

• 如果每個參與者都作了某些作業／回答某些題目。

• 那麼這些題目／作業便稱為重複量數（ repeated measures）。–或受試者內（ within subject）設計。

• 可以去除來自個體差異的 variance。

Example: 2-way repeated ANOVA

Source SS df MS FA A / (S*A)

B B / (S*B)

A*B A*B / (S*A*B)

S

S*A

S*B

S*A*B

Error

data aaa;

do S= 1 to 3;

do A=1 to 2;

do B=1 to 2;

input x @@;

output;

end;

end;

end;

datalines;

5 10 20 10

6 11 22 13

4 12 24 9

;

GLM for repeated measures

GLM for repeated measures: code

Between

ods graphics on;

proc glm data=AAA plots=intplot;

class A B;

model x=A|B;

run;

ods graphics off;

Between

proc glm data=AAA;

class A B S;

model x=A|B|S;

test h=A e=A*S;

test h=B e=B*S;

test h=A*B e=A*B*S;

run;

Result (between) : Interaction plot

Result (between)

Result (within)

DF 被model用完了，沒有 error可以除？

Result

Between

Mix models

• 有些變項是受試者內設計，有些變項是受試者間設計。

Example

• 16 dogs• Dependent variable:

– log-histamine concentration

• Independent variables:– Drug: morphine or trimethaphan (between)– Depleted: Y or N (between)– Time: measured after 0, 1, 3, or 5 min (within)

Codedata dogs;

input Drug $ Depleted $ Histamine0 Histamine1

Histamine3 Histamine5;

LogHistamine0=log(Histamine0);




datalines;

Morphine N .04 .20 .10 .08

Morphine N .02 .06 .02 .02

Morphine N .07 1.40 .48 .24

Morphine N .17 .57 .35 .24

Morphine Y .10 .09 .13 .14

Morphine Y .12 .11 .10 .

Morphine Y .07 .07 .06 .07

Morphine Y .05 .07 .06 .07

Trimethaphan N .03 .62 .31 .22

Trimethaphan N .03 1.05 .73 .60

Trimethaphan N .07 .83 1.07 .80

Trimethaphan N .09 3.13 2.06 1.23

Trimethaphan Y .10 .09 .09 .08




;

proc glm;

class Drug Depleted;

model LogHistamine0--LogHistamine5 =

Drug Depleted Drug*Depleted / nouni;

repeated Time 4 (0 1 3 5) polynomial / summary printe;

run;

先寫 betwwen，再寫 within

Missing data 不用

Result

Result

檢驗 Y在獨變項不同水準下的差異值變異數是否相同。

Sas tutorial glm2

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