Delurked and taken (finally); this is my first comment. I'd been wanting to take this survey for a while, but offline matters kept me away until now. At least I got in a good stab at most of the extra credit questions.

I second the following suggestions:

• Clarify the income question on tax status (pre-tax / post-tax / pre-some taxes and post-others) and individual vs. household. I mention the third tax possibility here because some taxes are deducted by the employer, so employees don't see that money in their paychecks. If the question intended is along the lines of "Other than tax refunds, how much money do you / your household receive (that you can use in a budget and could theoretically spend, although some of it may be set aside for further taxes) in a year?", then this matters.
• Add a "None" option to the mental illness question to distinguish between "none" and "didn't answer". Checkboxes would be nice, since mental illnesses can interact with each other, but Yvain has stated that he can't put them in the survey. I will mention this anyway in case checkboxes become viable for future versions of the survey.

I will also make a further suggestion, although I understand that it may be too onerous to implement: have an option to make only part of one's responses private. I mention this because I started by choosing the "public but anonymous" option, but switched to "private" once I got to the point that all my responses together could probably identify me out of the dataset if someone was moderately determined to do so and knew a few specific facts about me.

In my case, making a single extra credit section private (showing it as if I hadn't answered in the public dataset) would have been enough for me to be comfortable putting the remaining responses in the public dataset. That section has data that I don't mind giving Yvain and CFAR, but don't want to leave readily available to potential future agents trying to identify my responses in the dataset. I would prefer to make only the single section private, but I did not have that option available. I am also curious if other people are in the same boat.

Should I win, I precommit to spending the prize on myself, as per Yvain's stated wishes for the prize.