The relationship between the millivolt drop & temperature rise?

To comply to BS1363 for a 13A switched socket outlet, the mV drop at the L-contact after endurance should not be more than 75mV with temperature rise of not more than 45K loaded at 13A for 8 hours. Does this requirement mean that the mV drop vs the temperature rise of an electrical circuit should be at the ratio of 75/45 ? Is there any law or formula that states the value of temperature rise in correspond to the increase of every 1 mV drop ? Is it a sensible result that the L-contact of a socket with mV drop measured at 92 with the temperature rise of 38K loaded at 13A for 8 hours ?