Graph tip - How to create a column bar graph with error values (SD or SEM) calculated elsewhere and entered directly.

This example shows how to make a bar graph when you already have  your error information calculated.

How to do it:

When you create a new table and graph in Prism 5, one choice is to create a Column data table. Each column in the table creates one column in the graph, plotted as individual points, bars, box-and-whisker etc. This kind of graph can include error bars computed directly from the raw data you enter in each column. But there is no way to enter SD or SEM values computed elsewhere onto a column table.

If you want to enter SD or SEM values directly, start with a Grouped table instead of a Column table. With this kind of table, you can choose to format the table for direct entry of SD or SEM (and N) rather than raw replicates. 

This will create a data table with the appropriate columns. Use just the top row to enter your data.

If you enter data onto only one row of a Grouped data table, the graph will be almost the same as a column graph but with the error bars coming from SD or SEM values you entered directly. The difference is that Prism labels the graph like a Grouped graph, with different data sets identified with a legend, rather than column labels below each graph.

There are two ways to alter the graph to label each bar with its column title:

• Alternative 1: Click the Change graph type button, and change to a column bar graph. The data table will still be Grouped with subcolumns for SD or SEM, but now the graph will be Column, and so label each bar with its column title. 
• Alternative 2: Double-click on the X axis to bring up the Format Axis dialog. Change the Number format to 'Column titles."