RESEARCH AND ANALYSIS Exploratory Data Analysis of the Multilevel Anthropogenic Zinc Cycle T.E. Graedel, Marlen Bertram, and Barbara Reck Summary A comprehensive multilevel contemporary cycle for stocks and flows of zinc is analyzed by the tools of exploratory data analysis. The analysis is performed at three discrete organi- zational levels—country (53 countries and 1 country group that together comprise essentially all anthropogenic stocks and flows of zinc), world region (9 world regions), and the planet as a whole. The results demonstrate the following: (1) Exploratory data analysis provides valuable and otherwise un- obtainable information about material flows, especially those across multiple spatial levels. (2) All distributions of country- level zinc stock and flow data are highly skewed, a few coun- tries having large magnitudes, many having small magnitudes. (3) Rates of fabrication of zinc-containing products for the countries are poorly correlated with rates of extraction, re- flecting the fact that many countries that extract zinc do not fabricate products from zinc to any significant degree, and vice versa. (4) Virtually all countries are adding zinc to stock in the use phase (in galvanizing applications, zinc castings, etc.). These rates of addition are highly correlated with rates of zinc entering use in all regions, and are higher in regions under vigorous development. (5) With weak confidence, the rate of zinc landfilling by countries appears to be highly corre- lated with the rate of discard. (6) The statistical distributions of regional-level zinc cycle parameters are approximately log normal. (7) The extremes of normalized statistical distributions of zinc flow values are broader at lower spatial levels (country versus region, for example), but regional interquartile ranges for zinc entering use and zinc discards are higher at regional level then at country level. Keywords emergent behavior landfills recycling resource use substance flow analysis (SFA) waste management Address correspondence to: Professor Thomas E. Graedel Center for Industrial Ecology School of Forestry and Environmental Studies Yale University New Haven, CT 06511 USA <thomas.graedel@yale.edu> © 2005 by the Massachusetts Institute of Technology and Yale University Volume 9, Number 3 http://mitpress.mit.edu/jie Journal of Industrial Ecology 91