Description Usage Arguments Details References Examples

Implementation of a graphical device developed by Rex Galbraith to display several estimates of the same quantity that have different standard errors.

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`x` |
an object of class |

`num` |
index or name of the numerator variable |

`den` |
index or name of the denominator variable |

`from` |
minimum limit of the radial scale |

`to` |
maximum limit of the radial scale |

`t0` |
central value |

`sigdig` |
the number of significant digits of the numerical values reported in the title of the graphical output. |

`show.numbers` |
boolean flag ( |

`pch` |
plot character (default is a filled circle) |

`levels` |
a vector with additional values to be displayed as different background colours of the plot symbols. |

`clabel` |
label of the colour legend |

`bg` |
a vector of two background colours for the plot symbols.
If |

`title` |
add a title to the plot? |

`...` |
additional arguments to the generic |

The radial plot (Galbraith, 1988, 1990) is a graphical device that
was specifically designed to display heteroscedastic data, and is
constructed as follows. Consider a set of dates
*\{t_1,...,t_i,...,t_n\}* and uncertainties
*\{s[t_1],...,s[t_i],...,s[t_n]\}*. Define *z_i = z[t_i]*
to be a transformation of *t_i* (e.g., *z_i = log[t_i]*),
and let *s[z_i]* be its propagated analytical uncertainty
(i.e., *s[z_i] = s[t_i]/t_i* in the case of a logarithmic
transformation). Create a scatterplot of *(x_i,y_i)* values,
where *x_i = 1/s[z_i]* and *y_i = (z_i-z_\circ)/s[z_i]*,
where *z_\circ* is some reference value such as the mean. The
slope of a line connecting the origin of this scatterplot with any
of the *(x_i,y_i)*s is proportional to *z_i* and, hence,
the date *t_i*. These dates can be more easily visualised by
drawing a radial scale at some convenient distance from the origin
and annotating it with labelled ticks at the appropriate
angles. While the angular position of each data point represents
the date, its horizontal distance from the origin is proportional
to the precision. Imprecise measurements plot on the left hand side
of the radial plot, whereas precise age determinations are found
further towards the right. Thus, radial plots allow the observer to
assess both the magnitude and the precision of quantitative data in
one glance.

Galbraith, R.F., 1988. Graphical display of estimates having differing standard errors. Technometrics, 30(3), pp.271-281.

Galbraith, R.F., 1990. The radial plot: graphical assessment of spread in ages. International Journal of Radiation Applications and Instrumentation. Part D. Nuclear Tracks and Radiation Measurements, 17(3), pp.207-214.

Galbraith, R.F. and Laslett, G.M., 1993. Statistical models for mixed fission track ages. Nuclear Tracks and Radiation Measurements, 21(4), pp.459-470.

1 2 | ```
data(Namib)
radialplot(Namib$PT,components=c('Q','P'))
``` |

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