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Probability plot for von Mises distribution fitted to circular data

circpvmvarname[ifexp] [inrange] [, a(#)gridplot(plot)scatter_options]

Description

circpvmgives a probability (P-P) plot for the fit of a von Mises (a.k.a. circular normal) distribution to a circular variable on a scale between 0 and 360 degrees. circvm is used to fit the distribution, estimating the two parameters vector mean mu and concentration parameter kappa.For discussion, see Jammalamadaka and SenGupta (2001, pp.218-219); but note that some of their discussion of P-P plots applies to quantile-quantile plots (Q-Q plots), not P-P plots.

Options

a()specifiesain the formula for plotting position. The plotting positions are (i-a) / (n- 2a+ 1) for values ranked smallest to largest and assigned unique ranksi= 1, ...,n. The default isa= 0.5, giving (i- 0.5) /n. Other choices includea= 0, givingi/ (n+ 1), anda= 1/3, giving (i- 1/3) / (n+ 1/3).

gridis equivalent toyla(0(.25)1, grid) xla(0(.25)1, grid).

plot(plot)provides a way to add other plots to the generated graph; see help plot_option.

scatter_optionsare options of scatter.

Examples

. circpvm wallasp

ReferencesJammalamadaka, S.R. and SenGupta, A. 2001.

Topics in circularstatistics.Singapore: World Scientific.

AuthorNicholas J. Cox, University of Durham, U.K. n.j.cox@durham.ac.uk

Also seeOn-line: help for circvm, circqvm