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Visualization and Analysis Tools for Probabilistic Survey Data
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The Databrowsers described on these pages link probabilistic survey data to vetted statistical methods used by EPA scientists to summarize and interpret information derived from stream assessments.
All aspects of data management, statistical calculation and generation of plots are handled by software on EPA servers allowing users to focus on the science and what it means. By selecting unique combinations of regions, variables or analyses, users can make their own discoveries, test their ecological understanding, or try out a new analysis method.
Probabilistic Sampling Databrowser
EPA’s regional surveys were designed to collect data that are representative of conditions throughout the sampled area. Random site selection ensures that summary statistics derived from the data are unbiased and can be used to guide planning and management efforts at a regional scale.
This databrowser displays summary statistics for measures of biological condition, water chemistry, and site condition for wadeable streams. Users may test for correlation among response variables and human influence. Users may also subset the data and compare summary statistics and patterns of correlation according to year, state, stream order, or other factors.
Relative Risk Databrowser
Relative risk is a statistical method widely applied in human health reporting to summarize and compare the risk of developing an illness for a given set of factors. This approach has been adapted to summarize the effects of different stressors on the environmental health of streams. Because streams experience a variety of stressors (e.g., increases nutrients, loss of riparian habitat, sediment), resource managers need a method to identify which threats present the greatest risk in order to implement effective programs to protect them. Relative risk summarizes the strength of the association between a stressor and an indicator of stream condition.
This databrowser links relative risk calculations to the national Wadeable Streams Assessment data set. Benthic macroinvertebrates were used to assess stream condition. The databrowser allows users to compare the relative importance of various stressors across political or ecological regions.