Good work

I must congratulate bdjobs for introducing the best employer award in different categories. This will definitely encourage other organisations to improve the work environment.
But I was always under the impression that when a survey is conducted to understand the position of certain organization(s), sample data is collected from employees of those organisations, otherwise one will not get the correct information. According to bdjobs, among the participants 85.5% are currently employed (majority of the participants are not employed in any of the organisations finally coming out as winners), 6.5% are currently unemployed and around 8% are fresh graduates or students...
How can a) a participant comment/vote without having worked in any of the organisations? And b) what do 6.5% unemployed participants and 8% fresh graduates know about these employers?