The AstroStat Slog

From IMS Bulletin Vol. 36(3), p.11, Terence’s Stuff: Model skeptics

[Once I quoted an article by Prof. Terry Speed in IMS Bulletin: Data-Doctors. Reading his columns in the IMS Bulletin provides me an opportunity to reflect who I am as a statistician and some guidance for treating data. Although his ideas were not from astronomy or astronomical data analysis, I often find his thoughts and words can be shared with astronomers.]
Continue reading ‘[Quote] Model Skeptics’ »

X-ray summer school is on going. Numerous interesting topics were presented but not much about statistics (Only advice so far, “use implemented statistics in x-ray data reduction/analysis tools” and “it’s just a tool”). Nevertheless, I happened to talk two students extensively on their research topics, finding features from light curves. One was very empirical from comparing gamma ray burst trigger time to 24kHz observations and the other was statistical and algorithmic by using Bayesian Block. Sadly, I could not give them answers but the latter one dragged my attention.
Continue reading ‘Change Point Problem’ »

Much to everybody’s surprise, they let some astronomers into the recently concluded Joint Statistical Meeting at Salt Lake City, UT. There were two three astrostat sessions: [#45 on Probing the Universe with Nonparametric Methods,] #367 on Bayesian Applications in Astronomy and Physics (chaired by David van Dyk), and #411 on Image Analysis in Solar- and Astro-physics (chaired by Yaming Yu and Thomas Lee). Both [of the latter] sessions were dominated by presentations from CHASC collaborators.

From arxiv/astro-ph:0707.1891v1
The Geneva-Copenhagen Survey of the Solar neighborhood II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metalicity diagram, and heating mechanisms of the disk by Holmberg, Nordstrom, and Andersen

Researchers, including scientists from CHASC, working on color magnitude diagrams to infer ages, metalicities, temperatures, and other physical quantities of stars and stellar clusters may find this paper useful.
Continue reading ‘[ArXiv] Geneva-Copenhagen Survey, July 13, 2007’ »

Some of the lively discussion at the end of the first “Statistical Challenges in Modern Astronomy” conference, at Penn State in 1991, was captured in the proceedings (“General Discussion: Working on the Interface Between Statstics and Astronomy, Terry Speed (Moderator)”, in SCMA I, editors Eric D. Feigelson and G. Jogesh Babu, 1992, Springer-Verlag, New York,p 505).
Joseph Horowitz (Statistician):

…there should be serious collaboration between astronomers and statisticians. Statisticians should be involved from the beginning as real collaborators, not mere number crunchers. When I collaborate with anybody, astronomer or otherwise, I expect to be a full scientific equal and to get something out of it of value to statistics or mathematics, in addition to making a contribution to the collaborator’s field…

Jasper Wall (Astrophysicist):

…I feel strongly that the knowledge of statistics needs to come very early in the process. It is no good downstream when the paper is written. It is not even much good when you have built the instrument, because we should disabuse statisticians of any impression that the data coming from astronomical instruments are nice, pure, and clean. Each instrument has its very own particular filter, each person using that instrument puts another filter on it and each method of data acquisition does something else yet again. I get more and more concerned particularly at the present time [1991] of data explosion (the observatory I work with is getting 700 MBy per night!). There is discussion of data compression, cleaning on-line, and other treatments even before the observing astronomer gets the data. The knowledge of statistics and the knowledge of what happens to the data need to come extremely early in the process.