The AstroStat Slog

mini-Workshop on Computational Astro-statistics: Challenges and Methods for Massive Astronomical Data
Aug 24-25, 2010
Phillips Auditorium, CfA,
60 Garden St., Cambridge, MA 02138

URL: http://hea-www.harvard.edu/AstroStat/CAS2010
Continue reading ‘mini-Workshop on Computational AstroStatistics [announcement]’ »

This is a special session at the January 2010 meeting of the AAS. It is scheduled for the afternoon of Thursday, Jan 7, 2-3:30pm.

Abstracts are due Sep 17.

Meeting Justification

We propose to highlight the growing use of ‘non-parametric’ techniques to distill meaningful science from today’s astronomical data. Challenges range from Kuiper objects to cosmology. We have chosen just a few ‘teaching’ examples from this lively interdisciplinary area.

Continue reading ‘Beyond simple models-New methods for complex data’ »

I recently discovered iTunesU, and I have to confess, I find it utterly fascinating. By golly, it is everything that they promised us that the internet would be. Informative, entertaining, and educational. What are the odds?!? Anyway, while poking around the myriad lectures, courses, and talks that are now online, I came across a popular Physics lecture series at UMichigan which listed a talk by one of my favorite speakers, Owen Gingerich. He had spoken about The Four Myths of the Copernican Revolution last November. It was, how shall we say, riveting.

Owen talks in detail about how the Copernican model came to supplant the Ptolemaic model. In particular, he describes how Kepler went from Ptolemaic epicycles to elliptical orbits. Contrary to general impression, Kepler did not fit ellipses to Tycho Brahe’s observations of Mars. The ellipticity is far too small for it to be fittable! But rather, he used logical reasoning to first offset Earth’s epicyle away from the center in order to avoid the so-called Martian Catastrophe, and then used the phenomenological constraint of the law of equal areas to infer that the path must be an ellipse.

This process, along with Galileo’s advocacy for the heliocentric system, demonstrates a telling fact about how Astrophysics is done in practice. Hyunsook once lamented that astronomers seem to be rather trigger happy with correlations and regressions, and everyone knows they don’t constitute proof of anything, so why do they do it? Owen says about 39 1/2 minutes into the lecture:

Here we have the fourth of the myths, that Galileo’s telescopic observations finally proved the motion of the earth and thereby, at last, established the truth of the Copernican system.

What I want to assure you is that, in general, science does not operate by proofs. You hear that an awful lot, about science looking for propositions that can be falsified, that proof plays this big role.. uh-uh. It is coherence of explanation, understanding things that are well-knit together; the broader the framework of knitting the things together, the more we are able to believe it.

Exactly! We build models, often with little justification in terms of experimental proof, and muddle along trying to make it fit into a coherent narrative. This is why statistics is looked upon with suspicion among astronomers, and why for centuries our mantra has been “if it takes statistics to prove it, it isn’t real!”

The High Energy Astrophysics Division of the American Astronomical Society will meet at Los Angeles on March 31 – April 3, and we have been allocated a slot for an AstroStatistics session. It will be a 60-minute lunch-time session, so we anticipate that the session will be dominated by poster haikus and panel discussions similar to the workshop we held during the New Orleans meeting in 2004.

The meeting website is at: http://www.confcon.com/head2008/.The abstract submission deadline is January 25, 2008 (now past, but late abstracts are not unheard of among astronomers).

If you are attending the meeting, and plan to present posters or talks that deal with astrostatistical methods or techniques, we welcome you to participate in this session. When you submit an abstract, be sure to indicate a category of “Other” and in the comments field state that it belongs with the AstroStatistics special session.If you have questions, please contact Aneta or me. There is also a page for this session on the astrostat google groups site.

Update (1/22): The abstract submission page currently says that only one abstract is allowed per person. We have been informed that this is incorrect, and that people can submit two abstracts, one for the special session and one as a regular contribution. Note that posters will be up only one day, and those associated with a special session will be put up the day of the session.

Update (1/26): A detailed program is not yet available, but here is a description of the session:

Astrostatistics: Methods and Techniques

This session will provide a forum for the discussion and presentation of statistical challenges in high energy astrophysics, highlighting the great deal of progress that has been made in methods and techniques over the past decade. The one hour session will cover the current and future directions in Astrostatistics, and will include a discussion of MCMC methods in the context of specific applications (such as propagating calibration errors, defining the significance of image features, etc.); a discussion of standardized methods for computing detection limits, upper limits, and confidence intervals for weak sources; and hypothesis testing and its limitations (including the significance testing of emission lines).

Update (2/19): We have been allocated the mid-day slot of March 31. The session will run from 12:30pm till 1:30pm2pm. The tentative program is as follows:

• Remarks on current and future trends in AstroStatistics, by Eric Feigelson
• Poster haiku
• F-Test theory and usage, by David van Dyk
• Discussion on MCMC techniques, led by Andy Ptak

Update (2/26): The final program is out, and the AstroStat session is scheduled for 12:30pm-2pm at the Museum/Bunker Hill Room.

Update (4/1): The talks and posters associated with the AstroStat special session are now online at
http://hea-www.harvard.edu/AstroStat/HEAD2008/. Additional comments and descriptions will be archived there.

Quite interesting papers were up at arXiv, including a theoretical statistics paper that no astronomer manages to miss. To find the paper and others, please click
Continue reading ‘[ArXiv] 3rd week, Oct. 2007’ »

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.

In Spring 2006, SAMSI (Statistical and Applied Mathematical Sciences Institute) program on Astrostatistics began with tutorials, followed by workshops and regular meetings of working groups (Exoplanets, Surveys and Population Studies, Gravitational Lensing, Source Detection and Feature Detection, Particle Physics). Workshop speakers/participants and working group members brought up many statistical challenges in astronomy and physics and had extensive discussions. Summaries and relevant materials are available from the websites (click the links; some materials such as journal papers are password protected).

Since Summer 2005, G. Jogesh Babu (Statistics) and Eric Feigelson (Astronomy) have organized lectures and lab sessions on statistics for astronomers and physicists. Lecturers are professors from Penn State statistics department and invited renown scientists from different countries. Students show diverse demography as well. Within a week or so, students listen Statistics 101 to recently published statistical theories particularly applied to astronomical data. They also learn how to use R, a statistical software and script language to perform statistics they learn through lectures. Past two years, this summer school proved its uniqueness and usefulness. More information on the upcoming school can be found at http://astrostatistics.psu.edu/su07/index.html and other topics regarding astrostatistics at Center for AstroStatistics at Penn State.