  The structure of protoplanetary disks plays an essential role in planet
formation. Disks that are highly inclined, or ''edge-on'', are of particular
interest since their geometry provides a unique opportunity to study the disk's
vertical structure and radial extent. Candidate edge-on protoplanetary disks
are typically identified via their unique spectral energy distribution and
subsequently confirmed through high-resolution imaging. However, this selection
process is likely biased toward the largest, most massive disks, and the
resulting sample may not accurately represent the underlying disk population.
To investigate this, we generated a grid of protoplanetary disk models using
radiative transfer simulations and determined which sets of disk parameters
produce edge-on systems that could be recovered by aforementioned detection
techniques--i.e., identified by their spectral energy distribution and
confirmed through follow-up imaging with HST. In doing so, we adopt a
quantitative working definition of "edge-on disks" that is observation-driven
and agnostic about the disk inclination or other properties. Folding in
empirical disk demographics, we predict an occurrence rate of 6.2% for edge-on
disks and quantify biases towards highly inclined, massive disks. We also find
that edge-on disks are under-represented in samples of Spitzer-studied young
stellar objects, particularly for disks with M $\lesssim$ 0.5 $M_\odot$.
Overall, our analysis suggests that several dozen edge-on disks remain
undiscovered in nearby star-forming regions, and provides a universal selection
process to identify edge-on disks for consistent, population-level demographic
studies.
