Most people take these statistics where I work and are very reliable. Theyre so reliable than when you go take a salary negotiation they pull them out and say you should get around that and its not much more you can get usually. Unless the company is american. Then again 30-80% more than average is expected according to these surveys which have been correct so far everytime Ive used them.
Its so ridiculous than a newly graduated engineer that is lucky to work for an american company can get more salary than a person with 20 years experience in an average company. And thats why I created the post why do americans pay more even outside of America.