  Young stellar associations represent a key site for the study of star
formation, but to accurately compare observations to models of stellar
evolution, the age of an association must be determined. The Upper Scorpius
region is the youngest section of the Scorpius-Centaurus OB association, which
is the largest collection of nearby, young, low-mass stars. The true age of
Upper Scorpius is not clear, and an observed mass-dependent age gradient in
Upper Scorpius, as well as in other star-forming regions, complicates age
measurements. The age gradient may indicate a genuine astrophysical feature or
may be an artifact of unrecognized systematic effects in stellar age
measurements. We have conducted a synthetic red-optical low-resolution
spectroscopic survey of a simulated analog to the Upper Scorpius star-forming
region to investigate the effects of unresolved binary stars (which have
mass-dependent demographics) on age measurements of a stellar population. We
find that the observed mass-dependent age gradient in Upper Scorpius can be
explained by a population of undetected binary stars. For a simulated
population with an age of 10 (RMS = 2) Myr, we measure an age of 10.5 (RMS =
3.5) Myr for F stars, and 7.5 (RMS = 5.8) Myr for M stars. This discrepancy is
caused by the mass-dependent mass ratio distribution and the variable steepness
of the mass-luminosity relation. Our results support the previously suggested
10 Myr age for Upper Scorpius, with a small intrinsic age spread.
