NOAA / Space Weather Prediction Center

USAF Estimated Ap Index Quantile Plot

This conditional quantile plot shows the distribution of observed estimated Ap index values associated with forecasts grouped in 5-unit bins. The period covered is from 1986 to 2013. Distributions of the observed values are plotted on the Y-axis against 5-unit forecast bins along the X-axis. The observed distribution quantiles include the 10th, 25th (lower quartile), median, 75th (upper quartile), and 90th. A second graph directly below the quantile plot shows the number of forecasts in each bin. Note that the Y-axis of this lower graph is logarithmic.

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