VaR. Value-at-Risk for Linear Loss scenarios, i.e., α% percentile of Linear Loss scenarios.
Syntax
var_risk(α, matrix) |
short call |
var_risk_name(α, matrix) |
call with optional name |
Parameters
matrix is a Matrix of Scenarios:
where the header row contains names of variables (except scenario_probability, and scenario_benchmark). Other rows contain numerical data. The scenario_probability, and scenario_benchmark columns are optional.
is a confidence level.
Mathematical Definition
For continuous distributions, given and any specified probability level in the -VAR Risk for Loss equals
,
where is probability distribution function of the loss .
For discrete distributions, considered in PSG, when models are based on scenarios and finite sampling, calculation of VaR Risk for Loss includes the following steps:
1. Calculate the values of Loss Function for all scenarios
.
2. Sort scenarios so that
.
3. If then
If then: determine an index such that and .
4. If the index is such that the confidence level equals , then, VaR Risk for Loss equals
.
If then
If then VaR Risk for Loss equals linear interpolation between VaR Risks for Loss with confidence levels .
Example
Case Studies with VaR
See also
VaR Normal Independent, VaR Normal Dependent,
VaR Deviation, VaR Deviation Normal Independent, VaR Deviation Normal Dependent,
VaR for Mixture of Normal Independent, VaR Deviation for Mixture of Normal Independent