Canada census 2011: Not scientifically valid?

In Canada the abandonment of a compulsory national census has rocked the government. In Britain the Minister in charge of the 2011 census openly hopes it will be the last. Here Jon Baskerville discusses the Canadian experience; Jack Miles ponders an alternative for Britain; and Robert Groves, head of the US Census Bureau, describes his experiences and fears. On page 175 Neville Davies and Martha Aliaga use it for teaching.