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1. The reference condition approach to bioassessment is based on comparing a biological community found at a test site to the range of communities observed at a set of reference sites. A community descriptor (e.g. number of taxa) is estimated for the test site. If the value of the descriptor falls outside of a given boundary, or biocriterion, from the distribution of the descriptors for the reference sites, the test site fails. 2. The sensitivity of the reference condition approach can be increased by modelling and explaining variation in the community descriptor among the reference sites, and then using the predictive model to refine the expectation of the descriptor’s value at a test site. 3. This study applied the reference condition approach, with predictive modelling, to the bioassessment, using benthic macroinvertebrate (BMI) communities, of streams exposed to placer gold mining effluent in central Yukon Territory, Canada. The major changes to the stream caused by mining are increased turbidity and metal concentrations. 4. Among reference sites sampled from 1993 to 1995, a predictive model using year of sampling and simple geographical characteristics (distance to source of the stream, upstream catchment area, altitude, two‐way interactions) explained over half of the variation in each of five BMI community descriptors including richness (number of families), Simpson’s diversity, Simpson’s equitability, family biotic index and Bray–Curtis distance to the median reference community. 5. Biocriteria (other than Bray–Curtis distance to the median community) based on the predictive models failed a far greater proportion of sites currently exposed to placer mining (50–100%) than biocriteria not based on predictive models (7–71%). A similar increase in the sensitivity of the bioassessment was seen when evaluating sites previously exposed to placer mining effluent. The simplest, most sensitive bioassessment... [ABSTRACT FROM AUTHOR]

Objective: To compare the Household Food Insecurity Access Scale (HFIAS), the US Food Security Survey Module (US FSSM) and a modified version of the US FSSM in which references to buying food were changed to references to getting food, in terms of their classification of food security levels among homeless individuals, and to determine which of these instruments was most preferred by homeless individuals., Design: A cross-sectional survey., Setting: Recruitment of participants took place at seven shelters and from three drop-in programmes that serve homeless individuals in Toronto, Canada., Subjects: Fifty individuals who were ≥18 years of age, able to communicate in English and currently homeless., Results: The modified US FSSM assigned 20% of participants to a lower ordinal food security category compared with the US FSSM, and only 8% to a higher food security category. The HFIAS assigned 30% of participants to a lower food security category compared with either the US FSSM or the modified US FSSM, and only 10-16% of participants to a higher food security category. When asked to compare all three instruments, the majority of respondents (62%) selected the HFIAS as the best instrument for people who are homeless., Conclusions: A majority of homeless individuals selected the HFIAS as the best food security instrument for people who are homeless. Our findings suggest that the HFIAS is a more appropriate instrument than the US FSSM for measuring food security in the homeless population.