Statistical Distribution

Sir, I want to simulate one bow tie antenna with lumped source. I want to add noise to the source of the antenna that means changing setting as with this procedure: HFSS> design properties> click statistics> click distribution column> .... then after this I am unable to under stand what to do, which parameter distribution should be changed. Even I tried to change distribution of dimensional parameter of the source patch like length or width, but I am unable to see the impact one results. Now my questions are that (i) how to see the impact of changing setting of statistical distribution on results? (ii) which statistical distribution should be changed? (iii) how to see the impact of statistical distribution on results (iv) which result can show us the impact of statistical distribution change?
Thanks.