Solution
= Solution
Here $p=4$ and $n-p=96$. The supplied quantile gives
$$
F_{4,96}(0.9)=2.00.
$$
Since
$$
D_i=3.1>2.00,
$$
the coefficient estimate after deleting this observation lies outside the $90\%$ confidence ellipsoid centered at the full-data estimate. It also greatly exceeds the common rough reference value $D_i=1$. The observation is therefore highly influential and merits investigation:
$$
\boxed{\text{yes, its influence is concerning}.}
$$