The federal government's plan to change the Canadian census in 2011 will mean government and business won't have the information they need, a prominent Nova Scotia economist says.

Fred Morley, executive vice-president and chief economist of the Greater Halifax Partnership, said making the long-form census voluntary will decrease the quality of the data available about the Canadian population.

"We're going to look at a significant degrading of census data, " Morley said Thursday.

"Making it voluntary changes the whole dynamic. In fact, it creates a break in the data which means we can't look at trends anymore, we can't look at past information. It makes it more difficult to project into the future. It's bad in any number of different ways."

The Conservative government announced at the end of June that the long form part of the questionnaire will no longer be mandatory because of privacy concerns. Now, Canadians who receive the long form can refuse to fill it out.

P.O.V.: Census: Is it an invasion of privacy? Take our poll.

The 2006 census required about 20 per cent of Canadians to complete the long form which provides detailed household information used to decide everything from bus routes to new subdivisions to what support services are in local schools

Morley said businesses and government rely on the detailed census data when they decide where jobs are created or cut.

"They need good information. They need information they can rely on. If you don't have that, you make poor decisions," he said.

He said a voluntary census will also cost more money to promote if the government wants a good result.

Morley said the Conservatives are responding to a vocal fringe that distrusts government.

No consultation

"There's tremendous restrictions on this data and the use of this data. The general public probably gives out more, and more detailed, information when they fill out a ballot at a trade show," he said.

Morley said the government made the change without consulting any of the groups that use the data.

The co-ordinator of the Every Woman's Centre in Sydney said she is also against the plan to scrap the long census form.

Louise Smith-MacDonald said the data provided by those surveys are very useful.

"The long form gathers information that we feel is really necessary for a number of reasons. One, it helps to identify issues that people are living with," she said.

"And the other is that ... it provides a statistical record for us which is important to be able to have that information when we're applying for other funding and to run programs and to do some research."

Smith-MacDonald said she is worried that the poor and disadvantaged will statistically disappear if information on income is no longer rigorously collected in the census.

The Canadian Medical Association said Thursday that the census data are an essential tool in the delivery of health-care services to Canadians.