Jan 20th, 2009| 01:59 pm | Posted by hlee
Someone emailed me for globular cluster data sets I used in a proceeding paper, which was about how to determine the multi-modality (multiple populations) based on well known and new information criteria without binning the luminosity functions. I spent quite time to understand the data sets with suspicious numbers of globular cluster populations. On the other hand, obtaining globular cluster data sets was easy because of available data archives such as VizieR. Most data sets in charts/tables, I acquire those data from VizieR. In order to understand science behind those data sets, I check ADS. Well, actually it happens the other way around: check scientific background first to assess whether there is room for statistics, then search for available data sets. Continue reading ‘accessing data, easier than before but…’ »
Tags:
archive,
ascii,
catalog,
CDA,
data analysis,
data mining,
database,
Gator,
globular cluster,
inference,
massive data,
multimodality,
multiple populations,
NED,
SDSS,
statistical inference,
statistician,
streaming data,
table,
tabulated,
visieR Category:
Algorithms,
Astro,
Cross-Cultural,
Data Processing,
Jargon,
Meta,
Nuggets,
Objects |
3 Comments
Jul 8th, 2008| 07:27 pm | Posted by hlee
Astronomers confront with various censored and truncated data. Often these types of data are called after famous scientists who generalized them, like Eddington bias. When these censored or truncated data become the subject of study in statistics, instead of naming them, statisticians try to model them so that the uncertainty can be quantified. This area is called survival analysis. If your library has The American Statistician subscription and you are an astronomer handles censored or truncated data sets, this primer would be useful for briefly conceptualizing statistics jargon in survival analysis and for characterizing uncertainties residing in your data. Continue reading ‘Survival Analysis: A Primer’ »
Tags:
censored,
Efron,
Feigelson,
Freedman,
massive data,
Nelson,
Petrosian,
survival analysis,
truncated Category:
arXiv,
Fitting,
Stat |
4 Comments
Jul 25th, 2007| 01:46 pm | Posted by hlee
From arxiv/astro-ph:0707.3413
The Sixth Data Release of the Sloan Digital Sky Survey by … many people …
The sixth data release of the Sloan Digital Sky Survey (SDSS DR6) is available at http://www.sdss.org/dr6. Additionally, Catalog Archive Service (CAS) and
SQL interface to access the catalog would be useful to data searching statisticians. Simple SQL commends, which are well documented, could narrow down the size of data and the spatial coverage.
Continue reading ‘[ArXiv] SDSS DR6, July 23, 2007’ »
Tags:
catalog,
convex hull peeling,
density estimation,
DR6,
massive data,
multivariate analysis,
nonparametric,
SDSS,
SQL,
voronoi tessellation Category:
Algorithms,
arXiv,
Astro,
Data Processing,
Misc,
Optical |
1 Comment
Jul 2nd, 2007| 06:07 pm | Posted by hlee
From arXiv/astro-ph:0706.4484
Spectroscopic Surveys: Present by Yip. C. overviews recent spectroscopic sky surveys and spectral analysis techniques toward Virtual Observatories (VO). In addition that spectroscopic redshift measures increase like Moore’s law, the surveys tend to go deeper and aim completeness. Mainly elliptical galaxy formation has been studied due to more abundance compared to spirals and the galactic bimodality in color-color or color-magnitude diagrams is the result of the gas-rich mergers by blue mergers forming the red sequence. Principal component analysis has incorporated ratios of emission line-strengths for classifying Type-II AGN and star forming galaxies. LyЮБ identifies high z quasars and other spectral patterns over z reveal the history of the early universe and the characteristics of quasars. Also, the recent discovery of 10 satellites to the Milky Way is mentioned.
Continue reading ‘[ArXiv] Spectroscopic Survey, June 29, 2007’ »
Tags:
bimodality,
chi-square minimization,
Classification,
CMD,
Estimation,
machine learning,
massive data,
model based,
PCA,
spectral analysis,
spectroscopic,
survey,
VO Category:
arXiv,
Astro,
Bayesian,
Data Processing,
Fitting,
Frequentist,
Methods,
Spectral |
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