  We have studied the X-ray variability patterns and correlations of the radio
and X-ray fluxes in all spectral states of Cyg X-1 using X-ray data from
RXTE/ASM, CGRO/BATSE, and Swift/BAT. In the hard state, the dominant spectral
variability is a changing of normalisation with fixed spectral shape, while in
the intermediate state the slope changes, with a pivot point around 10 keV. In
the soft state, the low energy X-ray emission dominates the bolometric flux
which is only loosely correlated with the high energy emission. In black hole
binaries in the hard state, the radio flux is generally found to depend on a
power of the X-ray flux, F_R ~ F_X^p. We confirm this for Cyg X-1. Our new
finding is that this correlation extends to the intermediate and soft states
provided the broad-band X-ray flux in the Comptonization part of the spectrum
(excluding the blackbody component) is considered instead of a narrow-band
medium-energy X-ray flux. We find an index p=1.7+-0.1 for 15 GHz radio
emission, decreasing to p=1.5+-0. at 2.25 GHz. We conclude that the higher
value at 15 GHz is due to the effect of free-free absorption in the wind from
the companion. The intrinsic correlation index remains uncertain. However,
based on a theoretical model of the wind in Cyg X-1, it appears to be close to
1.3, which, in the framework of accretion/jet models, implies that the
accretion flow in Cyg X-1 is radiatively efficient. The correlation with the
flux due to Comptonization emission indicates that the radio jet is launched by
the hot electrons in the accretion flow in all spectral states of Cyg X-1. On
the other hand, we rule out the X-ray jet model. Finally, we find that the
index of the correlation, when measured using the X-ray flux in a narrow energy
band, strongly depends on the band chosen and is, in general, different from
that for either the bolometric flux or the flux in the hot-electron emission.
