As always, voluntary response data are worthless. https://news.ycombinator.com/item?id=5538059 Good luck to all of you looking for higher salaries. I hope you gain the salary you desire, and more knowledge of statistics along the way.
voluntary response data is flawed I agree, but I hesitate to call this worthless. I'd plaster warning signs all over the place alarming people to think through their reasoning and consider all the biases that would have taken place in the poll. (come to think of it, if the poll data incites that kind of skeptical thinking in some of its readers, that in itself might make the endeavor worthwhile)
I really don't mean to be rude, but that might just be because you don't understand statistics.