Unfolding is an ill-posed inverse problem in particle
physics aiming to infer a true particle-level spectrum from smeared
detector-level data. For computational and practical reasons, these
spaces are typically discretized using histograms, and the smearing
is modeled through a response matrix corresponding to a discretized
smearing kernel of the particle detector. This response matrix
depends on the unknown shape of the true spectrum, leading to a
fundamental systematic uncertainty in the unfolding problem. To
handle the ill-posed nature of the problem, common approaches
regularize the problem either directly via methods such as Tikhonov
regularization, or implicitly by using wide-bins in the true space
that match the resolution of the detector. Unfortunately, both of
these methods lead to a non-trivial bias in the unfolded estimator,
thereby hampering frequentist coverage guarantees for confidence
intervals constructed from these methods. We propose two new
approaches to addressing the bias in the wide-bin setting through
methods called One-at-a-time Strict Bounds (OSB) and Prior-Optimized
(PO) intervals. The OSB intervals are a bin-wise modification of an
existing guaranteed-coverage procedure, while the PO intervals are
based on a decision-theoretic view of the problem. Importantly, both
approaches provide well-calibrated frequentist confidence intervals
even in constrained and rank-deficient settings. These methods are
built upon a more general answer to the wide-bin bias problem,
involving unfolding with fine bins first, followed by constructing
confidence intervals for linear functionals of the fine-bin
counts. We test and compare these methods to other available
methodologies in a wide-bin deconvolution example and a realistic
particle physics simulation of unfolding a steeply falling particle
spectrum.