The truth (as well as my opinion) about scientific fitting procedures

Lovely  excerpt from Freeman Dyson’s essay  “A meeting with Enrico Fermi” in Nature 427, 297 (22 January 2004) (doi:10.1038/427297a).

“In desperation I asked Fermi whether he was not impressed by the agreement between our calculated numbers and his measured numbers. He replied, “How many arbitrary parameters did you use for your calculations?” I thought for a moment about our cut-off procedures and said, “Four.” He said, “I remember my friend Johnny von Neumann used to say, with four parameters I can fit an elephant, and with five I can make him wiggle his trunk.” With that, the conversation was over.”