We model the time variability of∼ 9000 spectroscopically confirmed quasars in SDSS Stripe
82 as a damped random walk (DRW). Using 2.7 million photometric measurements
collected over 10 yr, we confirm the results of Kelly et al. and Kozłowski et al. that this model
can explain quasar light curves at an impressive fidelity level (0.01–0.02 mag). The DRW
model provides a simple, fast (O (N) for N data points), and powerful statistical description of
quasar light curves by a characteristic timescale (τ) and an asymptotic rms variability on long …

We model the time variability of 9,000 spectroscopically confirmed quasars in SDSS stripe
82 as a damped random walk. We confirm the result of Kelly et al.(2009) that this model can
explain quasar light curves at an impressive fidelity level (0.01-0.02 mag). This model
provides a simple statistical description of a light curve using a characteristic time scale and
the amplitude of long-term variations. We search for correlations of these variability
parameters with various physical parameters such as luminosity, black hole mass, and rest …