44. The computer-readable recording medium according to claim 42 , wherein in the step (c), the plurality of units of analysis are generated by, for each unit of analysis, extracting a preset number of consecutive sentences from a plurality of consecutive sentences of the text information and generating the unit of analysis from the extracted consecutive sentences.
42. The computer-readable recording medium according to claim 41 , wherein the computer is further caused to execute the step of: (c) generating a plurality of the units of analysis from the text information, wherein in the step (b), the density is estimated for each unit of analysis generated in the step (c).