[en] In the framework of the extended Ginzburg-Landau model, the dependence of the multiplicity difference correlators F_q on phase space intervals δ is different in first-and second-order QGP phase transitions. Once ln F_q are expressed as functions of δ^1/3 and data-fitting by polynomials, one can determine the order of the phase transition by comparing the signs of the coefficients of the first power from fitting and from theoretical calculations. One virtue of this method is the independence of the unknown temperature parameter, and one can get the same information about the phase transition from one and higher dimensional analyses of the experimental data