Thanks for your reply.
As I understood, distribution and std deviation of the parameter is what the foundry provides (and may not explicitly specify the sigma value).
In such case, say I run and process+mismatch analysis and I want to target my design for 3 sigma, how many monte carlo iterations should i consider.
I read somewhere that when you target for 3 sigma, one needs to run for 1000 iterations, and find the mean and sample std deviation and multiply the sample std deviation by 3 if it is 3 sigma ? Is this procedure correct?