Results presentation: Posterior density plots (for individual parameters)

This page shows posterior probability density plots for the parameters you chose. These plots can be customized to suit your own tastes and requirements.

Accessing this page

This page is accessed from the format and parameter selection page by selecting "posterior probability density plots" as the results format type.

Description

This page shows posterior probability density plots for the parameters you have selected. Posterior probability density plots allow illustration of the estimate of the calendar date distributions for the parameters in question. Calendar years (cal BP or BC/AD depending on your calendar setting within the configuration page) are shown on the x-axis and the probability is shown on the y-axis.

Note: It is important to be aware that there is no 0 year within the BC/AD calendar. BCal takes this into account in all input/output. A side effect of this is that within individual parameter plots generated by BCal, the tics for years within the BC time scale may all end in 1. This is completely normal and does not represent a fault in the plotting software.

Note: The smoothness of the graph partly depends on the bin widths you set when you submit the job for calibration. If you want smoother (or less smooth) results you need to resubmit your job, setting the bin widths appropriately.

Below each plot are links to download the plots onto your computer. You may download the plots in the GIF (Graphical Interchange Format) and PBM (Portable BitMap file format) raster bitmap formats. These are suitable for loading into bitmap-based image processing and graphics packages. These may also be loaded into word processors. However, these images are not scalable and so may appear "jagged" when scaled. To overcome this, you may also download the plots in EPS (Encapsulated PostScript) format. This type of image is suitable for loading into word processors and typesetting programs. The image is scalable and so can be resized without loss of quality.

In addition to downloading images, you may also save a text file containing the marginal posterior probability data used to create the plots. This will be of use to you if you wish to use alternative plotting or statistical software to analyse the results. This text file is formatted into two columns. The first column contains the calendar year (cal BP). The second column contains the corresponding probability for that year. To download an image or data file you should right click on the appropriate link below the plot and select "Save As..." from the popup menu (there may be slight differences between browsers). A dialogue box will appear. You should provide a suitable name and location for the output file.

At the bottom of the page is a form. This form allows you to make changes to the plots shown on this page. After making any changes, selecting "Submit" redraws the plots with the settings you have provided. The settings available are as follows.

Year range - The range of years for the x-axis.

Automatic - If this box is checked the range will be calculated automatically. You should not provide values in the early and late fields.
Early - The latest year in the range. If the automatic box is checked, this value will be ignored.
Late - The earliest year in the range. If the automatic box is checked, this value will be ignored.

Probability range - The range of the probabilities to be plotted on the y-axis.

Automatic - If this box is checked the range will be calculated automatically. You should not provide values in the min. and max. fields.
Min - The minimum probability in the range. If the automatic box is checked, this value will be ignored.
Max. - The maximum probability in the range. If the automatic box is checked, this value will be ignored.

Image scaling - The amount of scaling used to determine the size of the images.

Horizontal - The amount of horizontal scaling to use. A value of 1 produces an image with width of 640 pixels.
Vertical - The amount of vertical scaling to use. A value of 1 produces an image with a height of 480 pixels.

Plot style - Sets the plotting style to use.

Dots - A dot is drawn for the probability value for each calendar year.
Boxes - A hollow box is drawn from the probability value for each calendar year down to the x-axis. This creates a bar chart effect.
Lines - A straight line is drawn between the probability values for each adjacent calendar years.
Points - A point is drawn for the probability value for each calendar year. The colour of this point depends upon the frequency of the points in the area surrounding this point. Where there is a high frequency of points a dark point is drawn. Where there is a low frequency of points a light point is drawn.

Grids lines - If this box is checked grid lines will be drawn on the image at the locations of the tics.
Title - The title for the plots. If this box is checked a title will automatically be generated for each plot. This title will contain the project name and the parameter label. If this box is not checked you must provide a title in the adjacent text field. This title will be used on all plots. Thus, if you want several plots with different customised labels you will need to select them one at a time on the parameter selection page.
Horizontal axis label - The label for the x (year) axis.
Vertical axis label - The label for the y (probability) axis.

You can return to the format and parameter selection page by selecting the "Back" button. Your choice of format and parameters will be restored.