Criterion for applying the new estimation method for the macro- and micropore effective diffusivities suggested by Song[6] was determined conservatively as θDp/Rp2>0.5 in terms of the single effective diffusivity by comparing the contour plot between the single and the two diffusivity models. It was confimed that making use of variance matching instead of skewness matching is desirable for model simplification even when a response curve exhibits a high degree of asymmetry about mean.