> ex_11_1.mod1 <- aov(y ~ a*b*c)
> anova(ex_11_1.mod1)
Analysis of Variance Table

Response: y
          Df Sum Sq Mean Sq F value Pr(>F)
a          1    0.5     0.5               
b          1  180.5   180.5               
c          1   40.5    40.5               
a:b        1   12.5    12.5               
a:c        1   24.5    24.5               
b:c        1   60.5    60.5               
a:b:c      1   12.5    12.5               
Residuals  0    0.0                       
Warning message:
In anova.lm(ex_11_1.mod1) :
  ANOVA F-tests on an essentially perfect fit are unreliable
> summary.lm(ex_11_1.mod1)

Call:
aov(formula = y ~ a * b * c)

Residuals:
ALL 8 residuals are 0: no residual degrees of freedom!

Coefficients:
            Estimate Std. Error t value Pr(>|t|)
(Intercept)    33.75         NA      NA       NA
a              -0.25         NA      NA       NA
b              -4.75         NA      NA       NA
c               2.25         NA      NA       NA
a:b             1.25         NA      NA       NA
a:c            -1.75         NA      NA       NA
b:c            -2.75         NA      NA       NA
a:b:c           1.25         NA      NA       NA

Residual standard error: NaN on 0 degrees of freedom
Multiple R-squared:     1,      Adjusted R-squared:   NaN 
F-statistic:   NaN on 7 and 0 DF,  p-value: NA 

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