On-line Machine Learning Lectures and Notes

hlee — Thu, 03 Jan 2008 18:44:14 +0000

I found this website a while ago but haven’t checked until now. They are quite useful by its contents (even pages of the lecture notes are properly flipped for you while the lecture is given). Increasing popularity of machine learning among astronomers will find more use of such lectures. If you have time to learn machine learning and other related subjects, please visit http://videolectures.net/. Specifically classified links to interesting subjects are found by your click.

Mathematics:
Mathematics>Operations Research (lectures by Gene Golub, Professor at Stanford and Lieven Vandenberghe, one of the authors of Convex Optimzation – a link to the pdf file)
Mathematics>Statistics (including Peter Bickel, Professor at UC Berkeley).

Physics:
Physics (You’ll see Randall Smith)

[In the near future, some selected lectures with summary note might be suggested; nevertheless, your recommendations are mostly welcome.]

What is so special about chi square in astronomy?

hlee — Thu, 12 Jul 2007 04:02:39 +0000

Since I start reading arxiv/astro-ph abstracts and a few relevant papers about a month ago, so often I see chi-square something as an optimization or statistical inference tool. Chi-square function, chi-square statistics, chi-square goodness-of-fit test are the words that serve different data analysis purposes but under the same prefix. As a newbie to statistics, although I learned chi-square distribution and chi-square test, doing statistics with chi-square are somewhat considered to be obsolete in terms of robust applications to modern data. These are introduced as one of many distributions and statistical tests. Nothing special. However, in astronomy, chi-square becomes the almost only method for statistical data analysis. I wonder how such strong bond between chi-square tactics and astronomer’s keen mind to data analysis has happened?

Beyond this historic question, one thing more bothers me is mixing chi-square function with chi-square distribution. The former is not necessarily chi-square distributed but it is practiced that once chi-square function is written, the variable within the function will have a confidence interval automatically according to chi-square distribution with degrees-of-freedom. No checking procedure for regularity conditions.

Statistically and astronomically, answers to my question lead to correcting my knowledge and erasing my prejudice. Vinay wrote about chi-square fitting. This certainly gives a better account for my question. Or Numerical Recipes to follow how chi-square methods are used. I welcome all kind lessons, advice, and references to have extended knowledge and a better perspective about the meaning of chi-square to astronomers.

The AstroStat Slog » optimization

On-line Machine Learning Lectures and Notes

What is so special about chi square in astronomy?