  Embedded clusters usually contain young stellar objects in different
evolutionary stages. We investigate number ratios of objects in these classes
in the star-forming regions rho Ophiuchi, Serpens, Taurus, Chamaeleon I, NGC
7129, IC 1396A, and IC 348. They are compared to the temporal evolution of
young stars in numerical simulations of gravoturbulent fragmentation in order
to constrain the models and to possibly determine the evolutionary stage of the
clusters. It turns out that Serpens is the youngest, and IC 348 the most
evolved cluster, although the time when the observations are best represented
varies strongly depending on the model. Furthermore, we find an inverse
correlation of the star formation efficiency (SFE) of the models with the Mach
number. However, the observational SFE values cannot be reproduced by the
current isothermal models. This argues for models that take into account
protostellar feedback processes and/or the effects of magnetic fields.
