A method for estimating molecule concentrations in a sample, the method including: obtaining a signal generated by a sample analyzing apparatus, the signal including at least one spectrum, the spectrum including peaks representative of the molecule concentrations in the sample and being expressed as a function of at least one variable; obtaining an analytical modeling of the signal with a modeling function, wherein the modeling function is based on the molecule concentrations and factors including gain factors of the equipment and description factors of the peaks; selecting uncertain factors in the factors; determining a priori probability distributions for the uncertain factors and the molecule concentrations; establishing, with the modeling function and the signal, posteriori probability distributions for the molecule concentrations and the uncertain factors; and estimating, with a processing module, the molecule concentrations and the uncertain factors from a parameter inferred from the posteriori probability distributions.