Joint distribution of intrinsic colors, observed colors, and velocities along with the intrinsic color locus for each color for the bimodal step simulation (Section 4.1). This simulation assumes a bimodal distribution of velocities (a mixture of two Gaussians), with a step function dependence of the mean intrinsic colors on velocities (black solid line) with some intrinsic scatter (black dashed lines). The observed colors (red points) are generated from the true intrinsic colors (blue points) by adding reddening due to dust extinction randomly drawn from an exponential distribution, A_V ~ Expon(τ = 0.3 mag) and by adding random measurement error.