[R] set seed for random draws

Md Desa, Zairul Nor Deana Binti zndeana at ku.edu
Sat Nov 5 01:38:20 CET 2011

Hello, all!
I need help on these two problems:

1) If I want to randomly draw numbers from standard normal (or other distributions) in loops e.g.:
 ty=0; ks=0
for (i in 1:5) {
        if (ty==0) {
            while ((ks<.2)||(ks>3)) {
            ks[i]-.3*k+.9 }

Question: Here I draw initial a, then if the drawn initial a satisfied 2 conditions I redraw a. I set.seed(13237) in the first draw of a, should I set.seed() in the redraw part?

2) I also have more loops after this i loop that also draw from normal(0,1). I want to randomly draws from normal(0,1) for loop j (inside loop j I draw another random numbers from N(0,1))
My question: Should I or shouldn't I set seed again and again for each loop? Why or why not.

I guess this problem concerned about setting seed as I want to have different number for each i.



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