Scale and Labels
The Options → Settings menu item allows the user
to customise the visual appearance of the graphical output. The
Settings dialog offers different options depending on
whether the Density Plot or Radial Plot option has been
selected in the Output menu. The settings can be saved by clicking
the 'save preferences for next time' checkbox.
Density Plots
Data can be visualised as KDEs, PDPs, histograms and points.
Any combination of these four elements can be selected by ticking the appropriate boxes.
Other options in the menu allow the user to specify the size of the
histogram bins, and to rescale the X-axis.
Pressing the Ctrl-button while clicking adjusts the vertical
scale. Thus, it is possible to 'zoom into' the density plot,
which is useful if one is interested in a minor peak of a particularly 'spiky'
distribution. The X-axis labels can be scaled and shortened using a multiplier
which is automatically calculated if the autoscale time labels option is selected.
This option is turned on by default for fission track data, and off for Other data.
The Settings panel allows the user to select which combination of
density estimators are to be included in the graphical output as either line
drawings or filled polygons:
- Kernel Density Estimate (KDE, turned on by default)
- Probability Density Plot (PDP, turned off by default for reasons given by Vermeesch, 2012)
- Histogram (turned on by default)
The values of the individual data points may be plotted by a combination of:
- Points: circles showing the values ignoring their analytical uncertainty
- Ticks: vertical lines whose length is proportional to the analytical precision
- Bells: curves indicating the analytical error distribution of the individual measurements
The Settings form also allows the user to specify the bandwidth
of the KDE if so desired (the automatic algorithm of Botev et al. 2010 is used
by default).
Radial Plots
The radial plots use a circular scale. The default values for the
minimum, maximum and central values (z0) can be changed in the
Options → Settings menu. Using a common
radial scale for different samples facilitates their intercomparison.
The Settings menu also contains a checkbox for adding
labels to the data points, providing an interpretive link between the
data table and radial plot. Single-grain ages and their uncertainties
can be determined by clicking anywhere on the radial plot window.
Pressing the Ctrl-button while clicking adjusts the horizontal
scale.
The upper left corner of the output window shows a data summary, including
the central age and age dispersion. This is an arguable better estimator of central
tendency than the arithmetic mean, because it takes into account the
lognormal nature of Ns/Ni and most age distributions.
Markers
Sometimes external age constraints are available which complement the data plotted
on a radial or density plot. For example, the depositional age of a sedimentary
deposit may be known, or a fission track dataset may be complemented by a U-Th-He
age. These external age constraints can be plotted alongside the data as marker lines.
The positions of the markers can be entered in the Settings menu as a
sequence of numbers separated by commas, semi-colons, colons, dashes, spaces, underscores
or plusses.