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Graphical Display

Overview of Plots

The graphical display of the results from the calculations and analysis is normally in the form of a multiple plot which is generated from the plot organiser document by pressing the button.

The form of the plots is generally determined by the stratigraphic relationships and the type of calculations performed. The plots are divided into up to four pages or groups of pages:

As well as the actual distributions details of the stratigraphic structure imposed on the data is also displayed down the left hand axis. This should allow anyone else wishing to repeat the calculations to see at a glance haw the data has been set up. A reference string is also printed at the top of the graph which indicates which calibration curve has been used and the important system options from the OxCal program.

Plot Options

There are a number of options which can be selected before a plot has been created. These are all accessed via the [View|Plot Options] menu item.

Options

These are altered through the dialog box:

Calibration data: whether or not to view the plots on the calibration curve and whether radiocarbon ages are given as percent modern or BP.

Show: you can decide whether to display the ranges (if they have been calculated); if the distributions are to be shown these can be solid black or in outline and there is an option to normalise all distributions to the same area; the prior distributions can be shown in outline on posterior plots.

X-Axis: the default is BC/AD - Calibrated BP or Radiocarbon BP can also be selected; the label can be omitted.

Multiple Plots: plots can be forced to be individual (this also displays convergence data if it has been included at the time of calculation); the analysis structure and agreement indices can be shown or not as required; the number of plots per chart can also be altered.

Once a plot has been created these aspects can be changed by reloading the plot using the button or [File|Options] on the plot viewer.

Style

These options allow you to control some aspects of the plot style. They can either be determined before plot creation by using the [View|Plot Options|Style] menu item or, after creation of an plot by using the [View|Style] menu item.

General: the relative size of the text can be altered; references and page numbers are optional as is the use of colour and italic labels for posterior distributions; the alignment grid is also optional.

Plotting can either be as smooth polygons (default) or as rectangular histograms.

Single Plots: whether or not to show the gaussian distribution and the calibration curve.

Correlation plots: solid fil and contour plots can be chosen.

Control over the Plotting Procedure

The form of the plots can be altered in four ways - each of which have their advantages:

Commands embedded in the model

The plot can to some extent be altered at the data input stage by inserting page breaks (Page), horizontal lines (Line) and labels (Label). The range of the axes can also be defined (Axis).

The advantage of this method is that if the model is changed slightly and recalculated the plots will still be properly formatted.

Modification in the plot organiser

The plot organiser can be used to re-order items, delete those that are not required etc.. Axis specifiers, page breaks, labels, lines and groupings can also be added at this stage by dragging the relevant icons from the selection in the right hand pane of the window:

The organisation you create can be saved with a different file name to ensure that it is not over-written by a repeat calculation. This gives considerable flexibility in arranging plots.

By raising the bar at the bottom of the window the text version of this plot organisation file can be viewed and changed. The format is given in the section on File Formats.

To access the raw data of the individual calibrations, right mouse click on the relevant icon in the plot organiser - this will bring up an editor window. This will not work if convergence data has been included as this makes the files too large to edit. See section on file formats.

Alteration of created plots

Once a plot has actually been created the scope for change is more limited but the axes can still be adjusted, the fonts changed, labels reworded etc.. Most of these changes are performed using the [View] menu menu of the plot viewer: More fundamental changes can also be made by using the button or [File|Options] but this will undo any changes made through the [View] menu.

Using Plots

The plots can be printed out directly using the [File|Print] menu item as with most Windows programs. You can also copy the plots onto the clipboard for pasting into word-processor files or other drawing packages using [Edit|Copy graphics].

Viewing the Calibration Curve

You can easily view the calibration curve by pressing the button. You can scroll around the calibration curve by clicking on the button: this will create a scroll control which allows you to look through the curve.

It is also possible to plot results on the calibration curve while viewing a plot after calculation in a subsidiary window. This is most easily achieved by using the button.