Probability distribution function (left) and cumulative distribution function (right) for radial velocity offsets from the mean velocity for velocities drawn from a Gaussian distribution with a dispersion of 1 km s^-1 (dotted, Eq. (2)), the velocity offsets expected due to binary orbital motions (dashed, Eqs. (3) and (4)), and the velocity distribution for a cluster with a velocity dispersion of 1 km s^-1 and a 100% binary fraction (solid), which is the convolution of the dotted and dashed distribution (Eq. (1)). Note that the binary orbital motions have a significant chance of giving a velocity offset of only tens of m/s, leading to a very high central peak in the probability density function, which has been cut off in the left panel.