How to Analyze Publication Time Trends by Correspondence Factor Analysis: Analysis of Publications by 48 Countries in 18 Disciplines over 12 Years

This study is a follow-up to a published Correspondence Factorial Analysis (CFA) of a dataset of over 6 million bibliometric entries (Dore et al. JASIS, 47(8), 588602,1996), which compared the publication output patterns of 48 countries in 18 disciplines over a 12-year period (1981-1992). It analyzes by methods suitable for investigating short time series how these output patterns evolved over the 12-year span. Three types of approach are described: (1) the chi distances of the publication output patterns from the center of gravity of the multidimensional system-which represents an average world pattern-were calculated for each country and for each year. We noted whether the patterns moved toward or away from the center with time; (2) individual annual output patterns were introduced as supplementary variables into an existing global overview covering the whole time-span [CFA map of (countries x disciplines)]. We observed how these patterns moved about within the map year by year; (3) the matrix (disciplines x time) was analyzed by CFA to derive time trends for each country. CFA revealed the "inner clocks" governing publication trends. The time scale that best fitted the data was not a linear but an elastic scale. Although different countries laid emphasis on publication in different disciplines, the overall tendency was toward greater uniformity in publication patterns with time.