1. A computer-implemented text analysis method comprising: accessing a plurality of text items regarding a plurality of different topics, wherein the text items were published over a time period; dividing the time period into a plurality of intervals; using dates of publication of the text items, associating the text items with the time intervals; for individual ones of the intervals, counting a number of the text items which include a given text pattern; comparing the counted numbers of text items which include the given text pattern for the individual intervals with one another; and identifying a topical change in the text items using results of the comparing.