## Estimated Errors

The error bar represents an estimate of the accuracy of the prediction.
The estimated error is based on the mathematical average of two sources of errors:
the geophysical variability (standard deviation) and the
standard error
of the mean.
The geophysical variability
is a measure of the scatter of the data used
to produce the model. This represents the standard deviation, or scatter,
about the mean, which is the error on the model prediction when applied
to a given location for a **particular** storm.
The standard error of the mean is the error of the fit to the data,
and represents how well the prediction matches the **average** ionospheric
storm response for a given location.
The tables of estimated errors show all three: the geophysical variability,
the standard error of the mean, and their mathematical average. The latter is the value used
on the ionospheric prediction display.

####
Table of Estimated Errors

Yesterday
Today

#### Sources of Estimated Errors

Standard Error of the Mean
Geophysical Variability (standard deviation)