What is nash-sutcliffe efficiency?

The Nash-Sutcliffe efficiency (NSE), also known as the Nash-Sutcliffe model efficiency coefficient, is a measure of the accuracy of predictive models. It is widely used in hydrology, ecology, and other fields to evaluate the performance of models that predict water flow, ecological processes, or other variables of interest. The NSE is a statistical measure that compares predicted values with observed values. It ranges from negative infinity to one, with one indicating a perfect fit between the predicted and observed values, and values close to or below zero indicating poor performance. The NSE is calculated as the ratio of the sum of squared differences between predicted and observed values to the sum of squared differences between observed values and their mean. A higher NSE indicates a better fit between predicted and observed values and hence a more accurate model. However, it is important to note that the NSE is not the only measure of predictive accuracy and should be used in conjunction with other metrics to evaluate model performance.