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Re-using expression
defining the exceedence level
and expression
defining the set
Xt(k,P) we extend definition
so that
|  |
(27) |
Note that here we have defined sets
against a universal set of a moving
sample of events rather than the entire out-of-sample set of events as expressed
in
. Next, using
defined as above, we can
construct booleans
and
such that:
|  |
(28) |
Clearly, through expression
, one can identify
that
and
are the BIS defined colour designation for
a risk model with respect to the assets on day t. As usual, the portfolio
represented by the superscripts covers the cases of the
long (+) or short (-) position in the US Dollar with respect to
the series k or portfolio P. Using the booleans defined by
expression
we can construct the colour frequency measures
| ![\begin{displaymath}
(G,R)^{\pm_{(k,P)}}(c) = {1\over751}\sum_{t\in[251,1001]}(G,R)_t^{\pm_{(k,P)}}(c)\\ \end{displaymath}](img459.gif) |
(29) |
where the notation (G,R) transparently refers to 2 expressions - one each for
and
respectively.
is of course the fraction of events in the out-of-sample
period when the green and red designation is applicable.
Note again that we have extended the BIS definition for this measure and allowed
confidence level c to be a variable.
Finally, as specified by expressions
and
,
we construct the univariate average BIS colour frequency
|  |
(30) |
and the multivariate average BIS colour frequency
|  |
(31) |
plotted in figures 2u and 2m respectively for all candidate models.
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