Evaluation of the Greenland AMAP programme 1994-1995, by use of power analysis (illustrated by selected heavy metals and POPs)

The levels of PCBs, HCB, HCHs, DDTs, Cd, Pb, Hg and Se, and especially the variability in biota obtained during Phase 1 of the Greenland AMAP-programm e have been used to illustrate the ability of the programme to detect diffe rences in contaminant levels over time. The statistical power of t-tests of contaminant levels are illustrated according to various scenarios of magni tude of change, significance level and sample size. The statistical power o f various time series of contaminant levels to detect linear trends in mean log-concentrations, including a random between-year variation component, i s illustrated. We conclude that the ability to detect differences is rather poor for many combinations of contaminants and media, and that long time s eries are needed before temporal trends are likely to be detected. (C) 2000 Elsevier Science B.V. All rights reserved.