The survey, commissioned by the federal privacy commissioner, showed 45 percent of those questioned had, at one time or another, declined to give their personal data to a retailer, the Canadian Broadcast Corp. reported Friday. About the same percentage of Canadians also said they have questioned a retailer about why they needed a name, postal code or address.

Those surveyed said they were reluctant to provide such information because of the possibility of fraud and identity theft.

About a quarter of the respondents could see no reason for the retailer needed the data, and 13 percent provided false information, the pollsters learned.

"Our personal information is increasingly invaluable in the marketplace, and I am very pleased to hear that consumers are taking charge and questioning requests for their information," Privacy Commissioner Jennifer Stoddart said Thursday in a news release.

"I recognize that businesses have a need to better know and understand their customers, but if they can't give you a good reason for why they need your personal information, simply don't give it out."

The telephone survey of about 1,000 adults was conducted by Ipsos-Reid Dec. 11-16, 2007. The margin of error is 3.1 percentage points.