OTo calculate prices under the risk-neutral measure Q, however, a few more steps are
required. Since the market is incomplete, there will be many equivalent martingales Q.
We find arbitrage-free prices for rainfall derivatives by using an equivalent martingale
measure Q = Q via the Esscher transform, which requires an additional parameter
, the MPR. For this, the type of the distribution of the simulated index outcomes is
determined and the parameters are fitted to the data. As the distribution is non-normal,
an Esscher transform of the distribution is performed with constant MPR. The mean
of this transformed distribution then leads to the expected price under the risk-neutral
measure Q, where is calibrated to the market data.
Details for these steps are explained in the following sections.