Charlottetown MP Shawn Murphy says the elimination of the mandatory long census form will mean government will get a less accurate picture of Canadians.
The Liberal MP expressed concern about the change, saying it could affect federal funding to some groups, including Acadians, aboriginal people and people with disabilities.
Murphy noted the importance of long-form information in making decisions.
"Everything really comes back to demographics…what people do, where they live, what they work at," Murphy said. "You can't measure, you can't manage, and this is going to really affect Canadian society in the long run."
The federal Conservative government plans to scrap the mandatory long census form and replace it with a voluntary national household survey.
Under the plan, everyone would still receive a mandatory short census form; one in three households would receive the longer survey.
While this new survey would actually go out to more people, its voluntary nature raises questions about how many Canadians would actually complete it.
Murphy said the federal government should re-instate the mandatory long-form census.
He added scrapping it could also affect equalization payments to provinces.
P.E.I. Finance Minister Wes Sheridan has also expressed his concerns about the changes.
Sheridan said the province uses information from the long-form census to make decisions about programs.
He said the P.E.I. government could end up with skewed information on Islanders, whether it's related to their incomes and education levels, the number of people staying home with children or seniors, ethnicity or languages.
Sheridan is sending a letter to Ottawa outlining his concerns.