1. A computer system comprising a plurality of configurations of a computer to operate in association with each other to assist a user in reviewing relevance of a large amount of documents, the plurality of configurations of the computer comprising: a processor; a memory in communication with the processor; a data storage device storing a document data comprising a plurality of documents; and a display in communication with the processor; wherein the memory has stored thereon instructions that, when executed by the processor, causes the processor to: a. extract a document group from the document data, the document group including one or more documents to be reviewed by the user, b. display the documents on the display; c. for each of the displayed documents, accept result information designated by the user, wherein the result information includes a plurality of classification codes according to a degree of relevance of the document, wherein the user assigns one or more of the classification codes to the document in accordance with a result of the review of the document; d. extract one or more elements appearing in each of the displayed documents, wherein the elements are morphemes constituting the displayed documents, e. calculate an evaluation value of each of the extracted elements, wherein the evaluation value is a characteristic value indicating a dependency between the element and the result information corresponding to the displayed documents; f. select a specified number of elements other than the elements previously selected, from among the one or more extracted elements, in descending order of evaluation values of the elements; g. calculate a score of each of the documents in the document data based on the selected elements and the evaluation values of the selected elements, and h. calculate a recall ratio based on the score, the recall ratio defining reproducibility of the result of the review performed by the user and a percentage of of documents having the calculated score greater than a predefined threshold value and belonging to the document group, as a result of arranging the documents in descending order of the scores; wherein the processor repeats the processes e-h until the recall ratio exceeds a unique target value.
7. The computer system according to claim 1 , wherein the processor calculates the recall ratio by calculating a rate of documents of the document group in predetermined percentage of documents having the score selected from top in descending order of the score.