It seems many groups want including the city want the long-form census compulsory because they say if it was voluntary the quality of information would be no good. I dispute that argument on two points.
First, years ago when I started as a junior accountant at a large company, the first day on the job someone dropped a bundle of forms on my desk. They were StatsCan reports that needed filling out and the most junior person got the job. So the person who knew the least, completed the surveys.
The reason. The survey's were compulsory and the company didn't get paid to provide the information, so what information they did provide, was going to be at the least cost, and therefore the least accurate. In my conversations with others in the business world, this is generally how StatsCan surveys are treated. Fill them out as cheaply as you can - accuracy isn't that important.
My second point is that the long-form census carries the threat of prosecution if you don't fill it out. So, in a sense, you are being coerced to providing the information. Again it has been shown that information obtained by threats is usually whatever the person trying to extract it wants to hear, not necessarily the truth.
So, my position is the information provided by the compulsory census was probably inaccurate anyway, and that a voluntary survey may be more accurate because people are providing the information willingly, rather than under penalty of fine or jail.