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Learn key control indicators and factors for operational loss data modeling, quality assurance, severity frequency modeling, and optimizing risk management practices.
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AMAzing Results first lessons from implementations of Basel IIRISK 07Gerhard Stahl, BaFin Sydney December 11, 2006 Seite 1
Database Modelling Data Model Control Environment Factors Key Control Indicators Operational Loss Data • data sources: • internal data • external consortium • external collection of publicly known cases Sydney December 11, 2006 | 15.09.2014 Seite 2
Database Modelling • data quality assurance: • internal data: data collection processes • external consortium: the custodian’s quality assurance • external publicly known: collection bias • identification of relevant loss data: • boundary to credit, market, timing or irrelevant losses • “acceptance” and possibly splitting of losses: assigning external losses to own business lines • key risk indicators / control environment factors: • often less reliable as an input to modelling • nevertheless important risk control Sydney December 11, 2006 | 15.09.2014 Seite 3
Severity Frequency Stochastic Modelling Extreme Value Theory OpVaR • issues: • extrapolation beyond experience (to the 1000-year event) • how to “back-test” • “merging” of internal and external data, bias removal • infinite mean models? Sydney December 11, 2006 | 15.09.2014 Seite 4
facts: • almost all data external • three models: internal, logNormal, Pareto • 1000-year event (regulatory capital) at the edge of the experience (all external data combined!) • 5000-year event (economic capital) is beyond any experience Sydney December 11, 2006 | 15.09.2014 Seite 5
facts: • blue line is model, black dots are internal data • model is not conservative in this BL/ET cell • 1000-year event (regulatory capital) is beyond internal experience: corresponds to 0.6bp in this graph! • again: need to extrapolate from real loss experience to far tail -> “shape factor” Sydney December 11, 2006 | 15.09.2014 Seite 6
facts: • POT method, GPD fit, estimate of the shape factor for various tresholds • one cell of the BL/ET matrix • fit “looks good” • but xi>1 means infinite mean! • Embrechts & Nesl.: • mixing of incomparable data ? Sydney December 11, 2006 | 15.09.2014 Seite 7
Current state of OpRisk modelling at banks ... • ... lags business practice in P/C insurance: • little to none explicit modelling of accumulation alias dependencies • little to none modelling of “exposure” (tiny step would be to replace gross loss modelling by loss ratios) • little to none modelling of “explaining variables” (e.g. US versus non-US business) • risk models are qualitatively ill-prepared to allow optimization of insurance coverage • no modelling of “reserve risk” Sydney December 11, 2006 | 15.09.2014 Seite 8
Operational Risk Management • aggregation • allocation to business lines • qualitative adjustments • self-assessments • own scenarios Operational Risk Reporting, Control and Management Stress Testing and Scenario Analysis Sydney December 11, 2006 | 15.09.2014 Seite 9