Replace the census with data mining:

That door-to-door stuff is like using a Gestetner to duplicate something instead of  "right click-copy-print" with your mouse.

 Here's  another study showing that data mining cell phone traffic can, for example, tell planners what they need to know about where people work and relax, in what numbers, and the routes they follow.  One glance at the chart confirms your suspicions.  No more long form census interrogations are needed, just a little ingenuity in data scooping.

The University of Southampton study was reported at Science Daily News.