In June 2010 the government replaced the mandatory long-form portion of the 2011 census with a voluntary survey. Hundreds of groups attacked the move, which threatens to cost more, skew data and especially hurt the most vulnerable Canadians.

The head of Statistics Canada resigned in July 2010 after Industry Minister Tony Clement suggested the agency approved the decision.

For the 2006 census the 40-page long-form was sent to 1/5 of Canadian households. This year Statistics Canada will send the National Household Survey to 1/3 of Canadian homes.

The extra printing costs and an ad campaign to boost participation will cost $30 million.

The 2011 census will begin May 2.

"Many Canadians may interpret the voluntary long form as applying as well to the mandatory short form. This would create an unacceptable risk to the credibility of the population count..."

"Statistics Canada has assumed a response rate of 50% for the voluntary National Household Survey."

"Any significant change in the methods of a survey can affect the comparability of data over time. There is a real risk that this will be the case for the National Household Survey."

"...there is a substantial risk of non-response bias...there is certain to be some residual, significant bias that will be impossible to measure and correct."

"If the 2B census questionnaire had been a voluntary survey in 2006, the picture of the population of Canada that would have emerged seems to be different for sub groups of the population, based on citizenship, visible minority, language and education."