- "Two Screens are Better Than One" from Microsoft Research, which indicated productivity gains of 9-50%, or
- "The Virtues of a Second Screen" in the New York Times, which gave a figure of 20-30%.
That's why I was happy to come across this Pfeiffer Report (long version) which measures the productivity of using a 17-inch LCD vs. the 30-inch Apple Cinema Display. Sure, the report was paid for by Apple, but the results are pretty clear. For their experiments, they clearly defined tasks such as "Moving Files Between Folders" and "Full-Page Editing (InDesign)" - identical step sequences, executed three times each by trained professionals. They found productivity gains between 39 and 73%.
Finally, some hard numbers from systematic measurements. I hope one of the LCD manufacturers will soon get the idea to repeat this study for single-screen vs. dual-screen.