The AstroStat Slog » Hubble constant

my first AAS. I. Regression

hlee — Mon, 09 Jun 2008 00:38:27 +0000

My first impression from the 212th AAS meeting is that it’s planned for preparing IYA 2009 and many talks are about current and future project reviews and strategies to reach public (People kept saying to me that winter meetings are more grand with expanded topics). I cannot say I understand everything (If someone says no astronomers understand everything, I’ll be relieved) but thanks to the theme of the meeting, I was intelligently entertained enough in many respects. The downside of this intellectual stimulus is growing doubts. One of those doubts was regression analysis in astronomy.

I’m not going to name the session, the speaker, nor the topic. Only relevant story related to regression analysis.

One of sessions, a speaker showed a slide with a headline, … test H_o…. My expectation was that H_o indicated a null hypothesis related to the expansion of the universe so that he was going to do a hypothesis testing. I was wrong. This H_o was the Hubble constant and his plan was estimating it with his carefully executed astrometry.

After a few slides later, I saw a straight line overplotted on top of scattered points. If I dissect the given space into 4×4, the most of points were occupied in the lower left corner section, and there was only one point placed in the section of the upper right corner. This single point had the most leverage that determines the slope of the line. Without verification, such as using Cook’s distance, I wondered what would happen with the estimated slope. Even with that high leverage point, I wondered if he still could claim with real statistics that his slope (H_o) estimate prefers the model by Freedman to the model by Sandage? To my naive eyes, the differences between the estimated slope from data and the two theoretical slopes are hardly distinguishable.

I saw papers in astronomy/astrophysics that carefully explain caveats of regression analysis on their target data and describe statistical tests to show the differences and similarities. Probably, the speaker didn’t want to disturb the audience with boring statistics. Yet, this was one of the occasions where my doubts toward astronomers who practice statistics in their own ways without consulting scholarly works in statistics sufficiently. The other likelihood is that I myself is biased to see things. I bet I’m the only one who expected that …test H_o… would accompany a null hypothesis and hypothesis tests, instead of estimating the Hubble constant.

[ArXiv] 2nd week, Apr. 2008

hlee — Fri, 11 Apr 2008 06:21:41 +0000

Markov chain Monte Carlo became the most frequent and stable statistical application in astronomy. It will be useful collecting tutorials from both professions.

[astro-ph:0804.0620] Q. Wu et al.
Late transient acceleration of the universe in string theory on $S^{1}/Z_{2}$ (MCMC)
[astro-ph:0804.0692] Corless, Dobke & King
The Hubble constant from galaxy lenses: impacts of triaxiality and model degeneracies (MCMC, Bayesian Modeling)
[astro-ph:0804.0788] Zamfir, Sulentic, & Marziani
New Insights on the QSO Radio-Loud/Radio-Quiet Dichotomy: SDSS Spectra in the Context of the 4D Eigenvector1 Parameter Space
[astro-ph:0804.0965] Bloom, Butler, & Perley
Gamma-ray Bursts, Classified Physically (instead of statistics, it relies on physics to grow a (classification) tree)
[astro-ph:0804.1089] G.K.Skinner
The sensitivity of coded mask telescopes
[astro-ph:0804.1197] Bagla, Prasad and Khandai
Effects of the size of cosmological N-Body simulations on physical quantities – III: Skewness
[astro-ph:0804.1447] Marsh, Ireland, & Kucera
Bayesian Analysis of Solar Oscillations
[astro-ph:0804.1532] C. López-Sanjuan, C. E. García-Dabó, M. Balcells
A maximum likelihood method for bidimensional experimental distributions, and its application to the galaxy merger fraction
[astro-ph:0804.1536] V.J.Martinez (One of my favorite astronomers who brings in mathematics and statistics)
The Large Scale Structure in the Universe: From Power-Laws to Acoustic Peaks

[ArXiv] 1st week, Dec. 2007

hlee — Fri, 07 Dec 2007 19:15:04 +0000

There’s only one day in the first week of December with no preprint appearance. Dubbing the week of Dec. 2nd as the first week is hoped to be accepted.

[stat.ML:0711.4983]
A Method for Compressing Parameters in Bayesian Models with Application to Logistic Sequence Prediction Models L. Li and R. M. Neal
[astro-ph:0711.4886]
Requirements on PSF Calibration for Dark Energy from Cosmic Shear S. Paulin-Henriksson et.al.
[astro-ph:0711.4895]
The impact of going beyond the Maxwell distribution in direct dark matter detection rates J. D. Vergados, S. H. Hansen, and O. Host
[astro-ph:0712.0003]
The Galaxy Cross-Correlation Function as a Probe of the Spatial Distribution of Galactic Satellites J. Chen
[stat.ME:0712.0283]
Wavelet methods in statistics: Some recent developments and their applications A. Antoniadis
[stat.ML:0712.0189]
Summarization and Classification of Non-Poisson Point Processes J. Picka and M. Deng
[astro-ph:0712.0588]
SZ and CMB reconstruction using Generalized Morphological Component Analysis J. Bobin et. al.
[astro-ph:0712.0610]
X-Atlas: An Online Archive of Chandra’s Stellar High Energy Transmission Gratings Observations O. W. Westbrook et.al.
[astro-ph:0712.0618]
Precision of Hubble constant derived using black hole binary absolute distances and statistical redshift information C. L. MacLeod and C. J. Hogan