April 6th, 2004, 2:48 am
Sorry, I didn't notice your answer. Thanks a lot!However, I dont know why you call it -approx- MLE....as I understand in case when we have at most one jump per day (considering daily data) we can use ordinary MLE. The problem with MLE for continuous tim models is that we may have infinite number of jumps and so we have a mixture of normals, so likelihood function can take infinite values...here we have at most one jump, so we can use MLE.I have another question...How would you model jump size?For the data I examining most positive jumps are larger than negative. So jump model of the form where B is Bernulli and Y is normal is not suitable....because normal distribution is symmetric. So I use the double exponential model for modelling positive and negative jumps separately i.e. positive jumps have exponential distribution with parameted -a- and positive with parameter -b-. This is how jump sizes are modelled in Kou's jump diffusion model. I can't see why I can't use, say, lognormal distribution for jumps.....