  We present an elementary mathematical method to find the minimax estimator of
the Bernoulli proportion $\theta$ under the squared error loss when $\theta$
belongs to the restricted parameter space of the form $\Omega = [0, \eta]$ for
some pre-specified constant $0 \leq \eta \leq 1$. This problem is inspired from
the problem of estimating the rate of positive COVID-19 tests. The presented
results and applications would be useful materials for both instructors and
students when teaching point estimation in statistical or machine learning
courses.
