Observe that d.f.(SSEfull)=n−2, d.f.(SSEred)=n−1 and SSEred−SSEfull=SSR. $$F^\ast =\dfrac{\dfrac{SSE_{red}-SSE_{full}}{d.f.(SSE_{red})-d.f.(SSE_{full})}}{\dfrac{SSE_{fu...Observe that d.f.(SSEfull)=n−2, d.f.(SSEred)=n−1 and SSEred−SSEfull=SSR. F∗=SSEred−SSEfulld.f.(SSEred)−d.f.(SSEfull)SSEfulld.f.(SSEfull)=SSRd.f.(SSR)SSEd.f.(SSE)=MSRMSE Under normal error model, and under H0:β1=0,F∗ has the F distribution with (paired) degress of freedom (d.f.(SSEred)−d.f.(SSEfull),d.f.(SSEfull)).