Oct 28th, 2009| 09:29 am | Posted by hlee
As a part of exploring spatial distribution of particles/objects, not to approximate via Poisson process or Gaussian process (parametric), nor to impose hypotheses such as homogenous, isotropic, or uniform, various nonparametric methods somewhat dragged my attention for data exploration and preliminary analysis. Among various nonparametric methods, the one that I fell in love with is tessellation (state space approaches are excluded here). Computational speed wise, I believe tessellation is faster than kernel density estimation to estimate level sets for multivariate data. Furthermore, conceptually constructing polygons from tessellation is intuitively simple. However, coding and improving algorithms is beyond statistical research (check books titled or key-worded partially by computational geometry). Good news is that for computation and getting results, there are some freely available softwares, packages, and modules in various forms. Continue reading ‘[ArXiv] Voronoi Tessellations’ »
Tags:
data compression,
delanay tessellation,
density estimation,
image processing,
nonparametric,
spatial statistics,
van de Weygaert,
van Lieshout,
voronoi tessellation Category:
Algorithms,
arXiv,
Galaxies,
Methods |
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Feb 9th, 2009| 03:16 pm | Posted by hlee
There were (only) four articles from ADS whose abstracts contain the word semiparametric (none in titles). Therefore, semiparametric is not exactly [MADS] but almost [MADS]. One would like to say it is virtually [MADS] or quasi [MADS]. By introducing the term and providing rare examples in astronomy, I hope this scarce term semiparametric to be used adequately against its misguidance of astronomers to inappropriate usage for statistical inference with their data. Continue reading ‘[MADS] Semiparametric’ »
Dec 14th, 2007| 05:16 pm | Posted by hlee
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 |
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