Paulings electronegativity is a relative scale, based on the difference in electronegativity between X and Y, $\Delta EN = 0.102 \sqrt {\Delta}$, where $\Delta = (X-Y)_{measured}-(X-Y)_{theoretical}$ bond energies.
But what is the oxidation state of X and Y? Is it an average of the common oxidation states for each element, or is it simply the most common oxidation state? Or do I have it all wrong to begin with?