Depends on what the advertised service is and where the sig is posted.
Ok guys but i`m not necessarly measuring the conversion rate of 1 service/product (i can just do that my own, post my affiliate link on my signature and then count it with a link shortener or whatever, as ACCTseller pointed out).
What I actually want to measure is the efficiency of the signature space itself (and not the content what it advertises), if you get my idea.
Or in other words, what i want to measure is not this:
But this: