A method, system, and a web site for evaluating a bias of an expert influencing the evaluation process of a patent document have been provided. First, an input data is received with regard to one or more patent indices, characterizing different aspects of a test patent document, from a trusted expert and from the expert whose bias to be determined respectively, followed by the processing of the input data received from the trusted expert into a Patent Quality value PQp as a function of said patent indices, and the processing of the input data received from the expert, whose bias to be determined, into a Patent Quality value PQc as the same function of the patent indices, and calculating a bias coefficient, characterizing the bias of the expert, as a dependence on the PQp, PQc and the type of said function of the patent indices. A corresponding bias compensated system, method, computer program product, and a web site for evaluating a patent document have been also provided, wherein said function of the patent indices has been distorted so as to compensate for the bias of the expert.