Wondered about the 'childish' choice of underpants:

"Citizen scientists enable large-scale research.
The "Proof by Underpants" project demonstrates the potential of citizen science for research. Without the help of the many volunteers, a study of this scale across 1,000 sites would not have been possible. [...] The exceptionally high level of participation is also reflected in the authorship: Around 240 citizen scientists are listed as co-authors of the publication."

"The project was launched under the title “Proof by underpants,” and the extent of decomposition was termed the “Underpants Index” (UI)."

I guess the 'exceptional participation' was a small psychological study in it self. Seemed to work beautifully at least..

study