The dependence of maximum starspot amplitude and the amplitude distribution on stellar properties

We combine photometric data from field stars, plus over a dozen open clusters and associations, to explore how the maximum photometric amplitude (A_max) and the distribution of amplitudes varies with stellar properties. We find a complex variation of A_max with inverse Rossby number Ro^-1, which nevertheless can be modeled well with a simple model including an increase in A_max with rotation for low Ro^-1, and a maximum level. A_max may then be further affected by differential rotation and a decline at the highest Ro^-1. The distribution of A_spot below A_max varies with Ro^-1 : it peaks at low A_spot with a long tail towards A_max for low Ro^-1, but is more uniformly distributed at higher Ro^-1. We investigate further dependences of the A_spot distributions on stellar properties, and speculate on the source of these variations.