A simple accurate method for normalizing the absolute magnitude of measured relative rare‐gas excitation cross‐section data to published measurements of the first Townsend coefficient is presented. Using a code which solved the Boltzmann equation we have determined that the predicted first Townsend coefficient is a very sensitive function of the electron impact excitation cross section. In Ar and Kr we have found that a 10% change in the cross section results in a 30% change in the first Townsend coefficient.