  We study correlations betwen X-ray spectral index, strength of Compton
reflection, and X-ray and radio fluxes in accreting black holes (Seyferts and
black-hole binaries). We critically evaluate the evidence for the correlation
of the X-ray spectral index with the strength of Compton reflection and
consider in detail statistical and systematic effects that can affect it. We
study patterns of spectral variability (in particular, pivoting of a power law
spectrum) corresponding to the X-ray index-flux correlation. We also consider
implications of the form of observed X-ray spectra and their variability for
interpretation of the correlation between the radio and X-ray fluxes. Finally,
we discuss accretion geometries that can account for the correlations and their
overall theoretical interpretations.
