Abstract
Power analysis can be a valuable aid in the design of monitoringprograms. It requires an estimate of variance, which may come from a pilot study or an existing study in a similar habitat. For marine benthic infauna, natural variation in abundances canbe considerable, raising the question of reliability of varianceestimates. We used two existing monitoring programs to generatemultiple estimates of variance. These estimates were found to differ from nominated best estimates by 50% or more in 43% of cases, in turn leading to under or over-estimation of samplesize in the design of a notional monitoring program. The twostudies, from the same general area, using the same samplingmethods and spanning a similar time scale, gave estimatesvarying by more than an order of magnitude for 25% of taxa.We suggest that pilot studies for ecological monitoring programsof marine infauna should include at least two sampling times.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Alden, R. W., III, Dahiya, R. C. and Young, R. J., Jr.: 1982, ‘A method for the enumeration of zooplanktonsubsamples’, J. Exp. Mar. Biol. Ecol. 59, 185–206.
Andrew, N. L. and Mapstone, B. D.: 1987, ‘Sampling and the descriptionof spatial pattern in marine ecology’, Oceanogr. Mar. Biol. Ann. Rev. 25, 39–90.
Cassie, R. M.: 1971, ‘Sampling andstatistics’, in W. T. Edmondson and G. G. Winberg (eds), A Manual on Methods for the Assessment of Secondary Productivity in Fresh Waters. International Biological Programme Handbook No. 17. Blackwell Scientific Publications, Oxford. pp. 174–209.
Clarke, K. R.: 1993, ‘Non-parametric multivariate analyses of change in community structure’, Aust. J. Ecol. 18, 117–143.
Cohen, J.: 1988, ‘Statistical Power Analysis for the Behavioral Sciences’, (2nd ed.) Lawrence Erlbaum Associates Inc., Hillsdale, N.J.
Eberhardt, L. L.: 1978, ‘Appraising variability in population studies’, J. Wildl. Manage. 42, 207–238.
Fairweather, P.G.: 1991, ‘Statistical power and design requirements for environmental monitoring#x2019;, Aust. J.Mar. Freshwater Res. 42, 555–568.
Faul, F. and Erdfelder, E.: 1992, GPOWER: A Priori, Post-hoc and Compromise Power Analyses for MS-DOS (Version 2.0), Bonn University, Dep. of Psychology, Bonn, FRG.
Green, R. H.: 1989, ‘Power analysis and practical strategies for environmental monitoring’,Environ. Res. 50, 195–205.
Heidelbaugh,W. S. and Nelson,W. G.: 1996, ‘A power analysis of methods for assessment ofchange in seagrass cover’, Aquat. Bot. 53, 227–233.
Johnson, R. K.: 1998, ‘Spatiotemporal variability of temperate lakemacroinvertebrate communities: detection of impact’, Ecol. Appl. 8, 61–70.
Keough, M. J. and Mapstone, B. D.: 1995,‘Protocols for designing marine ecological monitoring programs associated with BEK mills’, National Pulp Mills Research Program, Technical Report No. 11. CSIRO, Canberra.
Keough, M. J. and Mapstone, B. D.: 1997, ‘Designing environmental monitoring for pulp millsin Australia’, Wat. Sci. Tech. 35(2#x2014;3), 397–404.
Mapstone, B. D.: 1995, ‘Scalable decision rules for environmental impactstudies: effect size, Type I, and Type II errors’, Ecol. Appl. 5, 401–410.
Marine Science and Ecology.: 1990, ‘Study of thediet of flathead Platycephalus bassensis and school whiting Sillago flindersi from the Gippsland coast, Victoria’, unpublished report to the Latrobe Valley Water and Sewerage Board.
McArdle, B. H. and Pawley, M. D. M.: 1994, ‘Cost Benefit Analysis in the Design of BiologicalMonitoring Programs: Is it Worth the Effort?’, in D. J. Fletcher and B. F. J. Manly (eds), Statistics in Ecology and Environmental Monitoring. Otago Conference Series 2. University of Otago Press, Dunedin.
Osenberg, C.W., Schmitt, R. J., Holbrook, S. J., Abu-Saba, K. E.and Flegal, A. R.: 1994, ‘Detection of environmental impacts: natural variability, effect size and power analysis’, Ecol. Appl. 4, 16–30.
Pearson, T. H., Gray, J. S and Johannessen, P. J.: 1983, ‘Objective selection of sensitive species indicative of pollution-induced changein benthic communities. 2. Data analyses’, Mar. Ecol. Prog. Ser. 12, 237–255.
Peterson, C. H., Kennicutt, M. C., II, Green, R. H., Montagna, P., Harper, D. E., Jr., Powell, E. N. and Roscigno, P. F.: 1996, ‘Ecological consequences of environmental perturbations associated with offshore hydrocarbon production: a perspective on long-term exposures in the Gulf of Mexico#x2019;, Can. J. Fish. Aquat. Sci. 53, 2637–2654.
Plymouth Marine Laboratory (NERC): 1994, PRIMER: Plymouth Routines in Multivariate Ecological Research (Version4.0), Plymouth, UK.
SPSS Inc.: 1997, SYSTAT 7.0 for Windows, Chicago, IL.
Warwick, R. M.: 1988, ‘The level of taxonomicdiscrimination required to detect pollution effects on marine benthic communities’, Mar. Pollut. Bull. 19, 259–268.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Carey, J.M., Keough, M.J. The Variability of Estimates of Variance, and Its Effect on Power Analysis in Monitoring Design. Environ Monit Assess 74, 225–241 (2002). https://doi.org/10.1023/A:1014280405278
Issue Date:
DOI: https://doi.org/10.1023/A:1014280405278