It is rare for government agencies or indeed any other body carrying out a formal and important survey to abandon the exercise once it has been started. Reliable statistics that have been carefully compiled are always useful, and can be used as data for a variety of different analyses.
So it is unfortunate that the mainland authorities apparently decided to abandon their research to find how many people could claim right of abode in Hong Kong after the Court of Final Appeal ruling in January. They concluded, perhaps not unreasonably, that since most of the applicants had been successfully barred from entry after the reinterpretation by the Standing Committee of the National People's Congress, there was no point in further investigation.
But if the SAR Government had admitted that it conducted two surveys of its own, with wildly differing conclusions, the findings from the mainland census could have confirmed which of those figures was the most accurate.
From the start, the survey method the Census and Statistics Department chose to accept as the most reliable was called into question.
But the department concluded that 1.6 million people were eligible for entry, and released the figure with a fanfare of emotive language, talking of floodgates and telling people that even if such a tide of humanity could be absorbed, residents would have to prepare for cuts in their standard of living.
The NPC, anxious to help preserve Hong Kong's way of life from this perceived threat, duly reinterpreted the legislative intent of the Basic Law.