I have constructed a simple linear model and performed both a Type II & III analysis of variance using the Anova() function from the car package. In the output, the Type III Anova includes an intercept, whereas no intercept is included in the Type II Anova.
Type II
Anova Table (Type II tests)
Response: Zero.Tillage
Sum Sq Df F value Pr(>F)
Gender 0.732 1 9.723 0.001844 **
Residuals 159.856 2123
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Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
Type III
Anova Table (Type III tests)
Response: Zero.Tillage
Sum Sq Df F value Pr(>F)
(Intercept) 2.037 1 27.055 2.167e-07 ***
Gender 0.732 1 9.723 0.001844 **
Residuals 159.856 2123
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Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
What is the reasoning behind this? How do I determine if the model intercept is significant if I want to use a Type II test?
