Washington, July 25 - What if you had a remote-sensing mechanism that could record how millions of people worldwide were feeling on any particular day?

That is exactly what Peter Dodds, mathematician and Chris Danforth, computer scientist at the University of Vermont (UVM), are set to do.

They have worked out ways of gauging collective happiness by monitoring bloggers' and other online writers' reports of how they were feeling.

Their methods show that the day of Michael Jackson's death was one of the unhappiest.

'The proliferation of personal online writing such as blogs gives us the opportunity to measure emotional levels,' said Danforth.

'Surveys have thrown up some useful information, but these are plagued by the unpleasant fact that people misreport their feelings,' informed Dodds.

The blog writers tend to be somewhat younger and more educated than average, writing from everywhere with an even distribution between genders and a high racial diversity, said a UVM release.

The results were reported this week in the Journal of Happiness Studies.