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Likelihood ratio
•
A method to assess whether an added parameter improves
the fit sufficiently
•
It is always true that:
•
The question is if L(X,b) is
sufficiently
larger:
•
Test with χ
2
distribution with df=difference in # of parameters
1
) , ( max
)
( max
,
bX
L
X
L
bX
X
) , (
max
) (
max
ln2
,
2
bXL
XL
bX
X