What does the Model Predict?
The atrazine models included for use on this web site to create maps and graphs are the models for the annual mean, annual modeled maximum, annual modeled maximum moving averages (21-, 60-, and 90-day durations) and the 5th, 25th, 50th, 75th and 95th percentiles of annual concentration; models for other percentiles are included in Stone and Gilliom (2009). For each of these annual concentration statistics, the models can be used to estimate the value for a particular stream, including confidence bounds on the estimate, or the probability that a particular value will be exceeded, such as a water-quality benchmark. Each of these options for applying the model has advantages for specific purposes. The modeled maximum concentration is expected to under predict the true annual maximum concentration. The sampling frequencies of the model devlopment sites were not sufficient to characterize the true annual maximum concentrations (Stone and others, 2008). When used to estimate the value of a c
