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help for circpvm
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Probability plot for von Mises distribution fitted to circular data

        circpvm varname [if exp] [in range] [, a(#) grid plot(plot)
                 scatter_options]


Description

    circpvm gives 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() specifies a in the formula for plotting position.  The plotting
        positions are (i - a) / (n - 2a + 1) for values ranked smallest to
        largest and assigned unique ranks i = 1, ..., n.  The default is a =
        0.5, giving (i - 0.5) / n.  Other choices include a = 0, giving i /
        (n + 1), and a = 1/3, giving (i - 1/3) / (n + 1/3).

    grid is equivalent to yla(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_options are options of scatter.


Examples

    . circpvm wallasp


References

    Jammalamadaka, S.R. and SenGupta, A. 2001.  Topics in circular
        statistics. Singapore: World Scientific.


Author

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


Also see

    On-line: help for circvm, circqvm