Historical Market Data
When we design a value-at-risk (VaR) measure, one of the first steps is to choose a key vector 1R. We need this before we can design a mapping procedure that will construct portfolio mappings 1P = θ(1R). We also need it before we can design an inference procedure that will characterize the conditional distribution of 1R.
There are various issues to consider in selecting what prices, interest rates, spreads or other variables to represent with key factors 1Ri. One of these is the availability of historical market data. An inference procedure requires historical data related to all key factors. If there is no historical data relating to a particular variable, it makes little sense to model that variable as a key factor.
In this chapter, we discuss types of historical market data that may be used by value-at-risk measures. We describe how data is collected over time, how it is filtered and cleaned of errors, and how it is converted into forms usable by an inference procedure.