Sample Sizes
A non-exceedance probability value of 0.8 is used as one of the streamflow conditions. This is to provide a feel for how the forecast system performs for high flows, in this case the top 20% of flows, when compared to all flow measurements. In the module we will use a "top 20%" label to indicate where the high flow conditions are being examined.
In these sample size plots, notice that there are far fewer data points for the high flow threshold. If a higher non-exceedance probability were chosen there would not be enough data points for robust verification statistics
We see here that for the Williamsburg point, there are between 200 and 250 data points for the high flow threshold. The number is similar for Newport.
