Solution
= Solution
No dominance says that mean yield is affine in the number of $A$ alleles:
$$
\mu_{aa}=\alpha,
\qquad
\mu_{Aa}=\alpha+\delta,
\qquad
\mu_{AA}=\alpha+2\delta.
$$
Equivalently, $2\mu_{Aa}=\mu_{aa}+\mu_{AA}$. Fit that reduced model and compare it with Model 1 using
``
r
model3 <- lm(yield ~ count, data = potato)
anova(model3, model1)
``
The resulting one-degree-of-freedom F-test tests the no-dominance constraint against unrestricted genotype means.