This menu provides facilities for summarizing data values that consist of directional observations recorded as angles between 0 and 360 degrees. Two tests of uniformity are calculated. The null hypothesis for both of these is that the observations come from a uniform distribution around the circle.
of angular sectors of equal size. The width and centre of the sectors are specified in the options. The sectors are centred by adding a multiple of the specified with. For example, if the width is 20 and the centre is 0 then the sectors will be centred at 0, 0+20, 0+2*20, and so on. The second test
which compares the observed distribution with the expected distribution from a von Mises distribution with mean direction and concentration parameter (kappa) taking the values estimated from the observations. The observed and expected values are calculated for grouped directional data defined by the
Available Data
This lists variates for specifying the angles that are to be summarized. Double-click on a name to copy it to the current input field; alternatively, you can type the name directly into the input field.
Angles
Provides a space for you to specify a variate containing the directional observations (in degrees).
Width of sectors (degrees)
Specifies the width of sectors (in degrees) into which to group the angles for calculation of the test of randomness and the chi-square goodness of fit statistic for the von Mises distribution.
Centre of sectors (degrees)
Specifies the centre (in degrees) of the sectors
Direction of Rayleigh test (degrees)
Provides a space for you to specify the direction for Rayleigh's test of uniformity against a unimodel alternative.
Display Summary
When selected the following summary statistics are displayed: number of observations, mean direction,
circular standard deviation, mean resultant length, skewness and estimate of the parameter Kappa (which provides the concentration parameter of the von Mises distribution for circular data).
Display Fitted Values for von Mises Distribution
When selected, a table of observed and expected counts for the fit of the von Mises distribution is displayed.
Circular Plot
When selected, a circular plot of the data is produced.
See Also