  We assemble a sample of 733 dwarf galaxies ($M_{\ast} \le 10^{9.5}
\text{M}_\odot$) with signatures of active galactic nuclei (AGN) and explore
the intersection between different AGN selection techniques. Objects in our
database are compiled from previous studies that identify AGN in dwarf galaxies
through spectroscopy, X-ray emission, infrared colors, and optical photometric
variability. We apply a uniform set of AGN diagnostic tools to the database
using archival data. We find that any single selection method captures no more
than half of the overall AGN population, and there is a general disagreement
amongst the AGN selection methods in this stellar mass regime. The largest
overlap between methods is found when both methods use optical spectroscopic
data. In contrast, the populations of AGN intersect the least when comparing
those methods that use photometric data at different wavelengths. These results
can be used to better constrain the active fraction in dwarf galaxies, which is
in turn an important constraint for black hole seed formation models. In a
follow-up paper, we will explore links between the effectiveness of each
selection technique and host galaxy properties.
