Mapping acidification research: A test of the co-word method

This paper extends the co-word method for mapping science, adopting new statistical and graphical methods to explore time-series data and the changing distribution of effort between different research themes. It also tests the reliability of the co-word method, comparing coword data on the acidification of the environment with data derived from a large scale interview study. Overall, the study increases our confidence in the reliability of the co-word method. In particular, it leads us to the following conclusions: (a) that the PASCAL database is representative, at least in the area of acidification research; (b) that indexer bias is negligible; and (c) that the co-word method satisfactorily identifies groups of research themes and the way in which these evolve.It is with deep sadness and regret thatJohn Law has to report the tragic and unexpected death ofJohn Whittaker. The present paper was partially drafted before his death and reports findings that were the result of a close three-year collaboration. The final draft is, however, the responsibility ofJohn Law alone.