StatsAngularDistanceTest

StatsAngularDistanceTest [/ALPH=significance /APRX=m /T=k /Q/Z /WSTR=waveListString ] [srcWave1, srcWave2, srcWave3... ]

The StatsAngularDistanceTest operation performs nonparametric tests on the angular distance between sample data and reference directions for two or more samples in individual waves. The angular distance is the shortest distance between two points on a circle (in radians). Specify the sample waves using /WSTR or by listing them following the flags. Set reference directions with /ANG, /ANGW, or the sample mean direction.

Flags

/ALPH=val

Sets the significance level (default 0.05).

/ANG={d1, d2 }

Sets reference directions (in radians) for two samples; for more than two samples use /ANGW.

/ANGM

Computes the mean direction of each sample and uses it as the reference direction.

/ANGW=dWave

Sets reference directions (in radians) for more than two samples using directions in dWave, which must be single or double precision.

/APRX=m

Controls the approximation method for computing the P-value in the case of two samples (Mann-Whitney Wilcoxon). See StatsWilcoxonRankTest for more details. The default value is 0, which may require long computation times if your sample size is large. Use /APRX=1 if you have a large sample and you expect ties in the data.

No results printed in the history area.

/T=k

Displays results in a table. k specifies the table behavior when it is closed.

k =0:	Normal with dialog (default).
k =1:	Kills with no dialog.
k =2:	Disables killing.

/TAIL=tail

tail is a bitwise parameter that controls tail handling.

Bit 0:	Lower tail.
Bit 1:	Upper tail (default).
Bit 2:	Two tail.

See Setting Bit Parameters for details about bit settings.

The P-Value corresponding to the last tail calculated will be entered in the table.

/WSTR=waveListString

Specifies a string containing a semicolon-separated list of waves that contain sample data. Use waveListString instead of listing each wave after the flags.

Ignores errors. V_flag will be set to -1 for any error and to zero otherwise.

Details

The inputs for StatsAngularDistanceTest are two or more waves each corresponding to individual sample. The waves must be single or double precision expressing the angles in radians. There is no restriction on the number of points or dimensionality of the waves but the data should not contain NaNs or INFs. We recommend that you use double precision waves, especially if there are ties in the data. The reference directions should also be in radians. For two samples, StatsAngularDistanceTest computes the angular distances between the input data and the reference directions and then uses the Mann-Whitney-Wilcoxon test (StatsWilcoxonRankTest). Results are stored in the W_WilcoxonTest wave and in the corresponding table. For more than two samples, StatsAngularDistanceTest uses the Kruskal-Wallis test, storing results in the wave W_KWTestResults wave in the current data folder.

V_flag will be set to -1 for any error and to zero otherwise.

References

See, in particular, Chapter 27 of:

Zar, J.H., Biostatistical Analysis, 4th ed., 929 pp., Prentice Hall, Englewood Cliffs, New Jersey, 1999.

Demos

Open Angular Distance Demo