Dear all,
I have 3 models (from simple to complex) and I want to compare them in order to
see if they fit equally well or not.
From the R prompt I am not able to see where I can get this information.
Let´s do an example:
fit1<- lm(response ~ stimulus + condition + stimulus:condition, data=scrd)
#EQUIVALE A lm(response ~ stimulus*condition, data=scrd)
fit2<- lm(response ~ stimulus + condition, data=scrd)
fit3<- lm(response ~ condition, data=scrd)
> anova(fit2, fit1) #compare models
Analysis of Variance Table
Model 1: response ~ stimulus + condition
Model 2: response ~ stimulus + condition + stimulus:condition
Res.Df RSS Df Sum of Sq F Pr(>F)
1 165 364.13
2 159 362.67 6 1.4650 0.1071 0.9955
> anova(fit3, fit2, fit1) #compare models
Analysis of Variance Table
Model 1: response ~ condition
Model 2: response ~ stimulus + condition
Model 3: response ~ stimulus + condition + stimulus:condition
Res.Df RSS Df Sum of Sq F Pr(>F)
1 171 382.78
2 165 364.13 6 18.650 1.3628 0.2328
3 159 362.67 6 1.465 0.1071 0.9955
How can I understand that the simple model fits as good as the complex model
(the one with the interaction)?
Thanks in advance
All the best
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