  We present an extension to the robust phase estimation protocol, which can
identify incorrect results that would otherwise lie outside the expected
statistical range. Robust phase estimation is increasingly a method of choice
for applications such as estimating the effective process parameters of noisy
hardware, but its robustness is dependent on the noise satisfying certain
threshold assumptions. We provide consistency checks that can indicate when
those thresholds have been violated, which can be difficult or impossible to
test directly. We test these consistency checks for several common noise
models, and identify two possible checks with high accuracy in locating the
point in a robust phase estimation run at which further estimates should not be
trusted. One of these checks may be chosen based on resource availability, or
they can be used together in order to provide additional verification.
