lovely reception, slightly less lovely weather

The RSS conference social programme got underway this evening with a lovely reception at the Sea Life Centre in Brighton. The centre is a large aquarium with a series of interesting displays of aquatic life, and the venue was open this evening only for participants of the conference. So we had the run of the place, enjoying juice, wine, and hors d'oeuvres, while marveling at the undersea world and reveling in the joy of renewing old acquaintances and making new ones.

Registration began this afternoon, and in typical sharp RSS fashion, it was well organized. I was in and out of registration in under a minute, but spent several very pleasant minutes afterward meeting and greeting RSS staff.

The weather got quite blustery and then rather wet this afternoon. Medium-sized waves crashed loudly against the beach and the Brighton Pier. It is a bit chilly as well, or so it seems to someone coming from the lingering summer weather in the US. Nonetheless, the coast and the town are spectacular, a great setting for the conference.

The scientific programme begins tomorrow with opening remarks from David Hand, RSS President and a plenary talk by Peter Donnelly of Oxford. We’ll all be there Brighton-early (sorry, I have a rather nasty addiction to puns).

Statistical Engineering and a theory that dates back to 1914

One of the best methods that I have come across which exemplifies the inductive-deductive iterative nature of statistical investigations (see my first post) dates back to 1914 – the so-called “Pi” theorem of E Buckingham; I will illustrate the use of the “Pi” theorem using the well known paper-helicopter experiment, which many people who have taught statistical methods to engineers will be familiar with. If we adopt a completely empirical approach, we might decide to run a response surface experiment to model the flight time of the helicopter as a function of various design parameters; three design parameters might require about 15 runs in the experiment to develop the transfer function. However, if we think for a minute about the physics, we know that the flight time will be a function of the mass of the helicopter, and the area swept out by the rotors, together with the force due to gravity, and the density of air – and all of these quantities are known. The application of the “Pi” theorem, which reduces the dimensionality of the problem, and does not require linearity to ensure dimensional consistency, reveals that the number of experimental runs can be reduced to about three. It is a mystery as to why the “Pi” theorem isn’t referenced in any of the classic texts on response surface methodology and design of experiments; is it because not enough statisticians are interested in engineering?