15. A non-transitory computer readable medium containing a program for causing a computer to execute information analysis using a plurality of linguistic expressions as an analysis target, the program causing the computer to execute: (a) a step of extracting time information included in each of a plurality of electronic documents including at least any one of the plurality of linguistic expressions and a relationship between the electronic documents in the plurality of electronic documents from the plurality of electronic documents; (b) a step of detecting a link between one linguistic expression and another linguistic expression in the plurality of linguistic expressions and an appearance time of the link based on the time information and the relationship between the electronic documents extracted in step (a), and generating link information specifying the detected link and the appearance time of the link; and (c) a step of specifying the number of appearances of links between the one linguistic expression and the other linguistic expression and an appearance time of each link based on the link information generated in step (b), and calculating a correlation value between the one linguistic expression and the other linguistic expression according to a degree that the link continuously appears by using the specified number of appearances of the link and the appearance time of each link, the calculation of the correlation value being made by using a function that increases depending on a difference between first appearance time of one link and second appearance time of another link.
15. A non-transitory computer readable medium containing a program for causing a computer to execute information analysis using a plurality of linguistic expressions as an analysis target, the program causing the computer to execute: (a) a step of extracting time information included in each of a plurality of electronic documents including at least any one of the plurality of linguistic expressions and a relationship between the electronic documents in the plurality of electronic documents from the plurality of electronic documents; (b) a step of detecting a link between one linguistic expression and another linguistic expression in the plurality of linguistic expressions and an appearance time of the link based on the time information and the relationship between the electronic documents extracted in step (a), and generating link information specifying the detected link and the appearance time of the link; and (c) a step of specifying the number of appearances of links between the one linguistic expression and the other linguistic expression and an appearance time of each link based on the link information generated in step (b), and calculating a correlation value between the one linguistic expression and the other linguistic expression according to a degree that the link continuously appears by using the specified number of appearances of the link and the appearance time of each link, the calculation of the correlation value being made by using a function that increases depending on a difference between first appearance time of one link and second appearance time of another link. 19. The non-transitory computer readable medium according to claim 15 , wherein step (b) comprises detecting either or both of a time included in the time information of the electronic document including the one linguistic expression and a time included in the time information of the electronic document including the other linguistic expression as the appearance time of the link.