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Wiley InterScience | |||||||||||||||||
  Freshwater BiologyVolume 52 Issue 1, Pages 98 - 111 Published Online: 28 Nov 2006 © 2010 Blackwell Publishing Ltd
Abstract | References | Full Text: HTML, PDF (Size: 577K) | Related Articles | Citation Tracking  Using biological metrics to score and evaluate sites: a nearest-neighbour reference condition approach Copyright 2007 The Authors, Journal compilation 2007 Blackwell Publishing Ltd KEYWORDS Benthic Assessment of Sediment • multimetric • River Invertebrate Prediction and Classification System • standards assessment • stressor–response Summary
1. Reference (i.e. least or minimally impaired) sites can provide important information about the expected range of biological metrics and can be used to establish impairment or non-impairment of a test site. A problem with using reference data is that biological metrics are affected by natural conditions. We present an approach that uses local information to adjust for natural conditions and a method for statistically evaluating condition at a test site using biological metrics. 2. Our method consists of four steps: selection of a distance measure to find neighbours of a test site, selecting natural variables to measure the distance, selection of the number of neighbours and calculating a scored metric. 3. We use a simulated example to illustrate when the nearest-neighbour approach improves classification of sites as reference or not reference. 4. Using a set of data from the Mid-Atlantic Highlands, we show that the nearest-neighbour method improved on the ability of a regression approach to correctly classify test sites known to be from a non-reference group without affecting the ability to correctly classify test sites known to be from the reference group. (Manuscript accepted 10 October 2006) | 
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Multiple Stressors Special Issue 
