SAS tutorial: ANOVA

作業 (目前 )沒有但考試會考的東西

• Full model/reduced model comparison• Multiple comparison• Post hoc analysis (regression)

PROC ANOVA

• CLASS– Names the classification variables to be used in the model.

• MODEL– dependents=effects </ options> 

• TEST– TEST <H= effects> E= effect

• MEANS– MEANS effects </ options> – Post hoc analysis for the effects specified.

• REPEATED; ABSORB; BY; FREQ; MANOVA

Example

DataY X1 X2 X3

SAS code

• proc anova data=cream;• class batch position starter;• model acidity=batch position starter;• means batch starter /scheffe;• run;

Result - Data

Result – Analysis of Variance

Result- Scheffe’s test (batch)

Result – Scheffe’s test (starter)

Example: Repeated measure

• 30 people• Interest in voting (5-point scale)• Measured in 10, 15, 20 years old

SAS codedata ex2;

do subject=1 to 30;

do age=1 to 3;

input interest @@;

output;

end;

end;

datalines;

1 1 3

1 1 3

...

proc anova data=ex2;

class age subject;

model interest=age subject age*subject;

test h=age e=age*subject;

run;

Result - Data

Result - ANOVA

Result

test h=age e=age*subject;

Another way

• proc anova data=ex2;• class age subject;• model interest=age subject;• run;

Result - ANOVA

Questions

• ANOVA跟 linear regression的差別• Mean squared error的期望值• Fixed effect/random effect