LPT - You can check to see if a survey is truly anonymous or not by submitting a response saying you have concerns about confidentiality, and see if they get back to you.

Don't include your name or contact info, submit it anonymously through whatever means they are providing (this applies mostly to electronic/email surveys).

If they get back to you to address your concerns about confidentiality, that means they knew it was you who submitted the response, which proves the survey was *not* confidential.