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This relative measure,
, is maximized when the distribution of events in
are predicted with the correct probability by the
model. Of course this applies strictly only when
is large. In figures 4u and 4m we have plotted data in steps of
starting from
up to
- which is for increasing
confidence levels but decreasing population of contributing events.
It is precisely because the robustness of the statistic is in question
for very high levels of confidence, that we have taken the approach of
visualizing the measure as a function of the confidence level. When one
model shows consistently superior performance than another in the entire
high confidence level range - can we be sure that it is a superior
model in the context of risk management.
The figures 4u and 4m inform
us about the relative performance of the models for events deemed improbable by
the model itself. As already discussed in section
the sets
for different models do not
refer to the same subset of
. The motivation of the next measure
is to evaluate how the model performs explicitly for large price moves and to
allow comparison of models over exactly the same data.
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