1. An evaluation method for determining an evaluation score of one data object based on evaluation scores of and links in related data objects, the links each permitting one data object to point to another data object, the evaluation method comprising: updating, by a processor and in response to an update made to a first data object, the evaluation values of one or more second data objects linked from at least the first data object, based on the evaluation score of the first data object; and determining, by the processor and in response to a reference request for one data object, the evaluation score of the requested data object, based on the evaluation scores of one or more third data objects having a link to the requested data object.