{smcl} {* 3may2004}{...} {hline} help for {hi:circpvm} {hline} {title:Probability plot for von Mises distribution fitted to circular data} {p 8 17 2} {cmd:circpvm} {it:varname} [{cmd:if} {it:exp}] [{cmd:in} {it:range}] [{cmd:, a(}{it:#}{cmd:)} {cmdab:g:rid} {cmd:plot(}{it:plot}{cmd:)} {it:scatter_options}] {title:Description} {p 4 4 2} {cmd: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. {help circvm} is used to fit the distribution, estimating the two parameters vector mean mu and concentration parameter kappa. {p 4 4 2}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. {title:Options} {p 4 8 2}{cmd:a()} specifies {it:a} in the formula for plotting position. The plotting positions are ({it:i} - {it:a}) / ({it:n} - 2{it:a} + 1) for values ranked smallest to largest and assigned unique ranks {it:i} = 1, ..., {it:n}. The default is {it:a} = 0.5, giving ({it:i} - 0.5) / {it:n}. Other choices include {it:a} = 0, giving {it:i} / ({it:n} + 1), and {it:a} = 1/3, giving ({it:i} - 1/3) / ({it:n} + 1/3). {p 4 8 2} {cmd:grid} is equivalent to {cmd:yla(0(.25)1, grid) xla(0(.25)1, grid)}. {p 4 8 2} {cmd:plot(}{it:plot}{cmd:)} provides a way to add other plots to the generated graph; see help {help plot_option}. {p 4 8 2} {it:scatter_options} are options of {help scatter}. {title:Examples} {p 4 4 2}{cmd:. circpvm wallasp} {title:References} {p 4 8 2} Jammalamadaka, S.R. and SenGupta, A. 2001. {it:Topics in circular statistics.} Singapore: World Scientific. {title:Author} {p 4 4 2}Nicholas J. Cox, University of Durham, U.K.{break} n.j.cox@durham.ac.uk {title:Also see} {p 4 13 2} On-line: help for {help circvm}, {help circqvm}