To remove the effects of divergent policies, the assumption is made that non-domestic rate revenues in Wales would have grown at the same rate per head as in England in the absence of devolution.
Er mwyn dileu’r effeithiau o wahaniaethau o ran polisi, rhagdybir y bydd y refeniw o Ardrethi Annomestig yng Nghymru wedi tyfu ar yr un gyfradd y pen ag yn Lloegr yn absenoldeb datganoli.