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VOStat: FAQ
What analyses can VOStat do?
 Transforming and subsetting the data

 Select cases
 Simple transform
 Plots and summaries

 Boxplot: A univariate plot giving
a rough idea of the distributions and outliers.
 Dotplot: Plotting values of the same
variable for different objects (e.g., densities
of different asteroids).
 Histogram: Univariate histogram.
 Averaged Shifted Histogram (ASH):
Univariate ASH.
 Scatterplot: A bivariate plot
allowing error bars.
 Make a pairs plot. This is
sometimes also called a ScatterPLOt Matrix or SPLOM.
 3D scatterplot
 Summary statistics
 Estimating distribution from data
 Histogram
 Averaged Shifted Histogram (ASH):
Univariate ASH.
 Empirical distributon function (ECDF)
 Kernel density estimation:
 1dimensional (fixed window width)
 1dimensional (adaptive window width)
 2dimensional
 Fiting parametric distribution
 Comparing data with distributions
 Normal plot
 Tests for normality
 1sample KS test. This is
useful for checking if a variable in your data set is
distributed according to some standard distribution.
 AndersonDarling test. This is
another test for checking if a variable in your data set is
distributed according to some standard distribution.
 2sample KS test to compare the
distributions of two
continuous variables in a data set.
 Chisquare 2 sample test to compare the
distributions of two
discrete variables in a data set.
 Some standard tests
 One sample ztest to compare the
mean of a variable with some given number. This test is
applicable only if you know (or have a very good
approximation for) the standard deviation of
your variable. (Requires Gaussianity assumption.)
 One sample ttest. Similar to
above, except that you do not need to know the standard deviation. (Requires Gaussianity assumption.)
 paired ttest for comparing the
means of two variables. (Requires Gaussianity assumption.)
 Wilcoxon's signed rank test (1
sample).
Much like one sample ttest, but without
the Gaussianity assumption.
 Wilcoxon's signed rank test (2
sample). Much like paired ttest, but without
the Gaussianity assumption.
 Regression
 Linear regression
 Nadaraya Watson local regression
 Major axis/orthogonal regression
 LOESS
 Linear quantile regression
 Robust regression using M estimation
 Robust regression using trimmed least squares
 TheilSen regression
 Multivariate methods
 Make a pairs plot. This is
sometimes also called a ScatterPLOt Matrix or SPLOM.
 Linear regression
 Principal component analysis
 Canonical correlation analysis
 Model based clustering
 Hierarchical clustering
 Spatial methods
 Variogram
 knearest neighbours and Moran's I testa
 Ripley's K and related measures
 Voronoi tesselation and adaptive 2D kernel
density estimation
 Directional statistics
 Plotting directional data
 Summarizing direction data
 Kernel density estimation
 Fitting a von Mises distribution
 Testing goodnessoffit with a von Mises distribution
 Testing goodnessoffit with uniform distribution
 Survival analysis

 Maximum likelihood KaplanMeier
estimate of the survival curve for censored data
 A bunch of tests for censored
data: Log rank, PetoPeto, KolmogorovSmirnov, Cramervon
Mises, and AndersonDarling tests
 Maximum likelihood
LyndenBellWoodroofe estimator
 Time series analysis

 Time series plotting with smoothing
 (Partial) AutoCorrelation Function (ACF
and PACF)
 Autoregressive modelling
 Periodogram with smoothing option
What data file formats are supported by VOStat?
VOStat is for analysis of catalog data (and not image/spectrum
data). VOStat reads ASCII (space/tab/comma separated) files, FITS files,
and VOTables.
VOStat uses different output formats for different purposes:
 graphical output: png, eps and pdf.
 tabular output: VO table (downloadable by
[right/command]clicking or via SAMP)
 R scripts: ASCII text, that you can copynpaste from
the webpage.
 R workspace: Binary R format.
How does VOStat handle mising
values?
Please see our missing data policy
for details.
What is SAMP?
SAMP stands form Simple Application Management Protocol. It is a
serverclient protocol designed to coordinate between various applications
running in the same machine. You may get the details here.
Which SAMP MTypes does VOStat
support?
samp.app.ping
samp.hub.disconnnect
samp.hub.event.metadata
samp.hub.event.shutdown
samp.hub.event.subscriptions
samp.hub.event.unregister
client.env.get
table.load.votable
How do I learn R?
You may start with these 6 lessons meant to introduce R to
astronomers:
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1 
2 
3 
4 
5 
6
]