Series of Raman spectra were measured for microcrystalline silicon thin film with variable crystallinity. Five sets of Raman spectra (corresponding to excitations at 325 nm, 442 nm, 514.5 nm, 632.8 nm and 785 nm wavelengths) were subjected to factor analysis which showed that each set of spectra consisted of just two independent spectral components. Decomposition of the measured Raman spectra into the amorphous and the microcrystalline components is illustrated for 514.5 nm and 632.8 nm excitations. Effect of the light scattering on absolute intensity of Raman spectra was identified even for excitation wavelength highly absorbed in the mixed phase silicon layers.