Sep 18th, 2008| 07:48 pm | Posted by hlee
Another deduced conclusion from reading preprints listed in arxiv/astro-ph is that astronomers tend to confuse classification and clustering and to mix up methodologies. They tend to think any algorithms from classification or clustering analysis serve their purpose since both analysis algorithms, no matter what, look like a black box. I mean a black box as in neural network, which is one of classification algorithms. Continue reading ‘Classification and Clustering’ »
Tags:
black box,
book,
catalog,
Classification,
clustering,
haste,
outliers,
R,
Robert Serfling,
semi-supervised learning,
survey Category:
Algorithms,
Astro,
Bad AstroStat,
Cross-Cultural,
Data Processing,
Frequentist,
Jargon,
Methods,
Stat,
arXiv |
Comment
Jun 19th, 2008| 11:42 pm | Posted by hlee
I was questioned by two attendees, acquainted before the AAS, if I can suggest them clustering methods relevant to their projects. After all, we spent quite a time to clarify the term clustering. Continue reading ‘my first AAS. IV. clustering’ »
May 26th, 2008| 02:59 pm | Posted by hlee
Tags:
clustering,
high dimension,
LF,
maximum likelihood,
multivariate,
Poisson,
Schechter,
zero count Category:
Bayesian,
Fitting,
MCMC,
Methods,
Stat,
arXiv |
Comment
Feb 13th, 2008| 03:41 pm | Posted by hlee
Last week, I was at Tufts colloquium and happened to have a conversation with a computer scientist about density based clustering. I understood density as probabilistic density and was recollecting a paper by Fraley and Raftery (Model-Based Clustering, Discriminant Analysis, and Density Estimation, JASA, 2002, 97, p.458) and other similar papers I saw in engineering journals like IEEE transactions. For a few moments, I felt uncomfortable and she explained that density meant “how dense observations are.” Density based clustering was meant to be distance based clustering, like k-means, minimum spanning tree, most likely nonparametric approaches. Continue reading ‘language barrier’ »
Jul 25th, 2007| 03:22 am | Posted by hlee
From arxiv/astro-ph:0705.4020v2
Statistical Evidence for Three classes of Gamma-ray Bursts by T. Chattopadhyay et. al.
In general, gamma-ray bursts (GRBs) are classified into two groups: long (>2 sec) and short (<2 sec) duration bursts. Nonetheless, there have been some studies including arxiv/astro-ph:0705.4020v2 that statistically proved the optimal existence of 3 clusters. The pioneer work of GRB clusterings was based on hierarchical clustering methods by Mukerjee et. al.(Three Types of Gamma-Ray Bursts)
Continue reading ‘[ArXiv] Three Classes of GRBs, July 21, 2007’ »