Correct, for example HotOrNot voting. If you eneter a profile url directly, you can vote but it would not be counted. If you are sent randomly to a profile(by s

Correct, for example HotOrNot voting. If you eneter a profile url directly, you can vote but it would not be counted. If you are sent randomly to a profile(by selecting "next random" button), then there is no self selection bias and your vote is counted.