Your company here — click to reach over 10,000 unique daily visitors

v.normal.1grass - Man Page

Tests for normality for vector points.


vector, statistics, points, point pattern


v.normal --help
v.normal [-rl] map=name  [layer=string]  tests=range[,range,...] column=name  [--help]  [--verbose]  [--quiet]  [--ui]



Use only points in current region


Lognormality instead of normality


Print usage summary


Verbose module output


Quiet module output


Force launching GUI dialog


map=name [required]

Name of vector map
Or data source for direct OGR access


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


v.normal computes tests of normality on vector points.


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


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



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: Tuesday May 14 13:41:22 2024

Main index | Vector index | Topics index | Keywords index | Graphical index | Full index

© 2003-2024 GRASS Development Team, GRASS GIS 8.3.2 Reference Manual


GRASS 8.3.2 GRASS GIS User's Manual