table of contents
v.normal(1grass) | GRASS GIS User's Manual | v.normal(1grass) |
NAME¶
v.normal - Tests for normality for vector points.
KEYWORDS¶
vector, statistics, points, point pattern
SYNOPSIS¶
v.normal
v.normal --help
v.normal [-rl] map=name
[layer=string] tests=range[,range,...]
column=name [--help] [--verbose]
[--quiet] [--ui]
Flags:¶
Parameters:¶
- map=name [required]
-
Name of vector map
Or data source for direct OGR access - layer=string
-
Layer number or name
Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
Default: 1 - tests=range[,range,...] [required]
-
Lists of tests (1-15)
E.g. 1,3-8,13 - column=name [required]
-
Name of attribute column
DESCRIPTION¶
v.normal computes tests of normality on vector points.
NOTES¶
The tests that v.normal performs are indexed below. The tests that are performed are specified by giving an index, ranges of indices, or multiple thereof.
- 1
- Sample skewness and kurtosis
- 2
- Geary’s a-statistic and an approximate normal transformation
- 3
- Extreme normal deviates
- 4
- D’Agostino’s D-statistic
- 5
- Modified Kuiper V-statistic
- 6
- Modified Watson U^2-statistic
- 7
- Durbin’s Exact Test (modified Kolmogorov)
- 8
- Modified Anderson-Darling statistic
- 9
- Modified Cramer-Von Mises W^2-statistic
- 10
- Kolmogorov-Smirnov D-statistic (modified for normality testing)
- 11
- Chi-Square test statistic (equal probability classes) and the number of degrees of freedom
- 12
- Shapiro-Wilk W Test
- 13
- Weisberg-Binghams W’’ (similar to Shapiro-Francia’s W’)
- 14
- Royston’s extension of W for large samples
- 15
- Kotz Separate-Families Test for Lognormality vs. Normality
EXAMPLE¶
Compute the sample skewness and kurtosis, Geary’s
a-statistic and an approximate normal transformation, extreme normal
deviates, and Royston’s W for the random vector points:
g.region raster=elevation -p v.random random n=200 v.db.addtable random column="elev double precision" v.what.rast random rast=elevation column=elev v.normal random tests=1-3,14 column=elev
SEE ALSO¶
v.univar
AUTHORS¶
James Darrell McCauley <darrell@mccauley-usa.com>,
when he was at: Agricultural Engineering Purdue University
SOURCE CODE¶
Available at: v.normal source code (history)
Accessed: Saturday Jul 27 17:08:48 2024
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GRASS 8.4.0 |