KNOWLEDGEBASE - ARTICLE #1469

Graph tip - Combining columns and points or a curve fit on an XY graph

Last modified March 30, 2009

Prism offers three ways to combine points and bars on one graph. This page shows how to make an XY graph and plot some data sets as spikes or bars. The second approach is to create two graphs and superimpose them on a page layout.  The third approach is to make a Grouped graph, but plot some data sets as points. 


How to do it:

Start by creating an  XY data table and enter your data. You can set up your data table with replicates and have Prism calculate your error values, or you can enter your error values directly.

 

This will create a standard XY graph.

Double click on the Y axis to open the Format Axes dialog. Go to the tab for a right Y axis and select a Standard Axis. This will create a new Y axis on the right side of the graph.

Then, go back to your graph and double click on the data set you want to plot against the new Y axis. This will open the Format Graph dialog. Check the option in the Additional Options section to plot a data set on the new Y axis. You can also change the settings in the Show Symbols and Show Bars sections to change the data set to show as bars on your graph instead of points.

Check the option to show bars/spikes, uncheck the box to show symbols. At the bottom select to plot this data set against the right Y axis. If you want error bars for the columns, choose the option to have them show Above only.

If  you want to fit a curve on the one data set, click Analyze and uncheck the other before you do your analysis.

Double click on any axis to format the colors, titles, range, etc.

Download this file if you would like to see how this graph was made.

Combining stacked bars with points or a curve fit.

Normally, when you want to make a stacked bar graph with Prism, you start with a grouped data table. If you want to combine stacked bars with a curve fit on an XY graph, you can't enter the stacked bar data directly as you do on a grouped graph, but you can to it with a little fussing. If you have two data sets plotted as spikes with the same x coordinate, they will be superimposed, which looks sort of stacked. If one data set is entered as the sum (the top of the stack) and the other as one component, they will look stacked. It may require some fussing with the order of data sets on the graph (format graph/data sets on graph tab).

Here is the data table. Use the second data column for the total of the stacked bars:

Download this file if you would like to see how this graph was made.


 

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