  In wireless communication networks, interference models are routinely used
for tasks such as performance analysis, optimization, and protocol design.
These tasks are heavily affected by the accuracy and tractability of the
interference models. Yet, quantifying the accuracy of these models remains a
major challenge. In this paper, we propose a new index for assessing the
accuracy of any interference model under any network scenario. Specifically, it
is based on a new index that quantifies the ability of any interference model
in correctly predicting harmful interference events, that is, link outages. We
consider a specific wireless scenario of both conventional sub-6~GHz and
millimeter-wave (mmWave) networks and demonstrate how our index yields insights
into the possibility of simplifying the set of dominant interferers, replacing
a Nakagami or Rayleigh random fading by an equivalent deterministic channel,
and ignoring antenna sidelobes. Our analysis reveals that in highly directional
antenna settings with obstructions, even simple interference models (such as
the classical protocol model) are accurate, while with omnidirectional
antennas, more sophisticated and complex interference models (such as the
classical physical model) are necessary. We further use the proposed index to
develop a simple interference model for mmWave networks that can significantly
simplify design principles of the important procedures for wireless
communication, such as beamforming, interference management, scheduling, and
topology control. Our new approach makes it possible to adopt the simplest
interference model of adequate accuracy for every wireless network.
