Archive for December 2008

[MADS] multiscale modeling

A few scientists in our group work on estimating the intensities of gamma ray observations from sky surveys. This work distinguishes from typical image processing which mostly concerns the point estimation of intensity at each pixel location and the size of overall white noise type error. Often times you will notice from image processing that the orthogonality between errors and sources, and the white noise assumptions. These assumptions are typical features in image processing utilities and modules. On the other hand, CHASC scientists relate more general and broad statistical inference problems in estimating the intensity map, like intensity uncertainties at each point and the scientifically informative display of the intensity map with uncertainty according to the Poisson count model and constraints from physics and the instrument, where the field, multiscale modeling is associated. Continue reading ‘[MADS] multiscale modeling’ »


We have seen the word “bipartisan” often during the election and during the on-going recession period. Sometimes, I think that the bipartisanship is not driven by politicians but it’s driven by media, commentator, and interpreters. Continue reading ‘Bipartisanship’ »


I do not rely much on my cell phone. It functions as a tool for confronting emergencies. On the other hand, it seems like people do lots of things with their smart phones and I like to add one thing to your “what I do with my phone.” Continue reading ‘Wapedia’ »


MADS stands for “Missing in ADS.” Every astronomer, I believe, knows what ADS is. As we have [EotW] series and used to have [ArXiv] series, creating a new series for semi-periodic postings under the well known name ADS seems interesting. Continue reading ‘[MADS] HMM’ »

Meet at January AAS meeting to organize a white paper for Astro2010

Hello Sloggers,

Every decade, the National Research Council (under the auspices of the National Academies) convenes a panel to survey the state of astronomy and astrophysics, and to recommend plans and funding priorities for the subsequent decade. The resulting Decadal Survey document has a profound influence on funding of astronomy research at every level. The process for the 2010 decadal survey has begun; Roger Blandford will discuss it at the January 2009 AAS meeting (AAS decadal survey session, Tues, 6 Jan, 8:30am). The National Academies web site hosts a page for the Astro2010 Decadal Survey with more information.

White papers authored by individuals and groups in the astronomical community are a major source of input for the review panel. I would like to lead the effort on a collaborative white paper urging explicit, targeted support for (interdisciplinary) astrostatistics research (perhaps broadened to “astroinformatics” or “astronomical data analysis”). I would like to meet with any of you who would like to co-sign such a white paper, and help author it (as your resources allow). I think the AAS meeting offers a great opportunity for us to meet in person to start fleshing out ideas for the white paper, to be subsequently fleshed out via online interaction.

Here I’d like to discuss when to meet at AAS. Note that some Sloggers are participating in an astrostatistics special session, “Meaning from Surveys and Population Studies”, Monday, 2-3:30pm. In principle, since some of us will already be gathered there, it could make sense to meet afterward somewhere; but there are important prize lectures right afterward that I, for one, would like to hear. Other possibilities include lunch or dinner that day (Monday), or perhaps lunch or dinner the next day, after we’ve all heard Roger Blandford’s presentation on how the survey will work this year.

I have some concrete ideas for the white paper, and I’m sure some of you do, too. But here and now, let’s not get into content; let’s just organize a meeting at AAS.

With that, the floor is open for suggestions on a good meeting time/venue.

Borel Cantelli Lemma for the Gaussian World

Almost two year long scrutinizing some publications by astronomers gave me enough impression that astronomers live in the Gaussian world. You are likely to object this statement by saying that astronomers know and use Poisson, binomial, Pareto (power laws), Weibull, exponential, Laplace (Cauchy), Gamma, and some other distributions.[1] This is true. I witness that these distributions are referred in many publications; however, when it comes to obtaining “BEST FIT estimates for the parameters of interest” and “their ERROR (BARS)”, suddenly everything goes back to the Gaussian world.[2]

Borel Cantelli Lemma (from Planet Math): because of mathematical symbols, a link was made but any probability books have the lemma with proofs and descriptions.

Continue reading ‘Borel Cantelli Lemma for the Gaussian World’ »

  1. It is a bit disappointing fact that not many mention the t distribution, even though less than 30 observations are available.[]
  2. To stay off this Gaussian world, some astronomers rely on Bayesian statistics and explicitly say that it is the only escape, which is sometimes true and sometimes not – I personally weigh more that Bayesians are not always more robust than frequentist methods as opposed to astronomers’ discussion about robust methods.[]