In this third paper in a series of three , we present a detailed study of the broadband spectral energy distribution ( SED ) of active galactic nuclei ( AGN ) based on a nearby unobscured Type 1 AGN sample .
We perform a systematic cross-correlation study of several key parameters , i.e . \Gamma _ { 2 - 10 keV } , L _ { 2 - 10 keV } , L _ { bol } / L _ { Edd } = \lambda _ { Edd } , L _ { bol } / L _ { 2 - 10 keV } = \kappa _ { 2 - 10 keV } , L _ { bol } / L _ { 5100 A } = \kappa _ { 5100 A } , FWHM _ { H \beta } , M _ { BH } , \alpha _ { ox } , \alpha _ { X } and \alpha _ { UV } .
The well defined spectral properties of the sample enable us to improve existing relations and to identify new correlations among these parameters .
We confirm a break region around FWHM _ { H \beta } \simeq 4000 km s ^ { -1 } in the \Gamma _ { 2 - 10 keV } vs. FWHM _ { H \beta } correlation and Log ( M _ { BH } ) \simeq 8.0 in the \Gamma _ { 2 - 10 keV } vs. M _ { BH } correlation , where these correlations appear to change form .
Beyond the break point the intrinsic \Gamma _ { 2 - 10 keV } index is dispersed around 1.8 .
Several new correlations are also reported in this paper e.g .
strong correlations in \kappa _ { 5100 } vs . \lambda _ { Edd } , \kappa _ { 5100 } vs . \kappa _ { 2 - 10 keV } and \kappa _ { 2 - 10 keV } vs. M _ { BH } .
The principal component analysis ( PCA ) is performed on the correlation matrix of the above parameters .
This shows that the three physical parameters , i.e .
black hole mass , mass accretion rate and Eddington ratio , drive the majority of the correlations .
This is consistent with PCA results found from previous optical spectral studies .

For each key parameter , we split the AGN into three sub-samples , binned based on increasing value of that parameter .
We co-add the model SEDs for each object in the sub-sample to see how the SED changes with that parameter .
Most parameters , except L _ { bol } , show similar systematic changes in the SED such that the temperature at which the disc peaks is correlated with the ratio of power in the disc versus the Comptonised components and the hard X-ray spectral index .
This underlying change in SED shape shows that AGN do exhibit intrinsically different spectral states .
This is superficially similar to the SED differences in BHB ( black hole binary ) seen as \lambda _ { Edd } increases , but the analogy does not hold in detail .
Only objects with the highest \lambda _ { Edd } appear to correspond to a BHB spectral state ( the disc dominated high/soft state ) .
The AGN with typical mass accretion rates have spectra which do not match well with any state observed in BHB .
We speculate that this could be due to the presence of a powerful UV line driven disc wind , which complicates simple mass scaling between stellar and supermassive black holes .