Could someone explain me or suggest a good reference how to categorize the PD calculation methods without going to deep in the details?
I learned on riskmanagement lecture, that there are three major approaches, the sturctural models, the rating based method and it is also possible to estimate from cds spread. On a separate course we slightly touched cds pricing. We were told it is possible to use structural or intensity (reduced form) models. And usually it is done in reverse manner, calibrate the model for the market prices.
I understand, that they are conceptualy different approaches, but I don't see the big picture. The methods which I mention in the later paragraph are refeering to the estimation from cds spreads? Lastly I would like to ask about the correlation. I know that one method is the gaussian copula, but this could be applied for any model?
Thanks and sorry if I've been a bit unorderd