Paper presents analysis of sensitivity of parameters of Jiles-Atherton model determined during the optimization process. Recently implemented, differential evolution based method together with two-step optimization process proved, that parameters of Jiles-Atherton model can be determined in reasonable time. However, paper indicates, that in the case of isotropic materials, Bloch domain wall interaction coefficient. has too insignificant influence on the shape of hysteresis loop to be determined during the optimization. As a result, for fundamental physics analyses,. should be estimated on the base of physical properties of magnetic material.