Using microlensing measurements from a sample of 27 image-pairs of 19 lensed quasars we determine a maximum likelihood estimate for the accretion disk size of an average quasar of r_s=4.0^+2.4_-3.1 light days at rest frame <λ>=1736Å for microlenses with a mean mass of =0.3M_. This value, in good agreement with previous results from smaller samples, is roughly a factor of 5 greater than the predictions of the standard thin disk model. The individual size estimates for the 19 quasars in our

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... are also in excellent agreement with the results of the joint maximum likelihood analysis.