  The current study aims to examine uncertainty relations for measurements from
generalized equiangular tight frames. Informationally overcomplete measurements
are a valuable tool in quantum information processing, including tomography and
state estimation. The maximal sets of mutually unbiased bases are the most
common case of such measurements. The existence of $d+1$ mutually unbiased
bases is proved for $d$ being a prime power. More general classes of
informationally overcomplete measurements have been proposed for various
purposes. Measurements of interest are typically characterized by some inner
structure maintaining the required properties. It leads to restrictions imposed
on generated probabilities. To apply the considered measurements, these
restrictions should be converted into information-theoretic terms. It is
interesting that certain restrictions hold irrespectively to overcompleteness.
To describe the amount of uncertainty quantitatively, we use the Tsallis and
R\'{e}nyi entropies as well as probabilities of separate outcomes. The obtained
results are based on estimation of the index of coincidence. The derived
relations are briefly exemplified.
