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.

Column Data Table

When you create a new table and graph in Prism, 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. You also have the option to enter data as mean, error, and sample size (N). 

For example, here is a dataset with three groups (A, B, and C) where we have entered mean, standard deviation (SD), and sample size (N). Note that this format requires subcolumns, so a Grouped data table is created.

And here is the resulting graph.

Grouped Data Table

If you want to enter SD or SEM values directly, you can also start with a Grouped data 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. Enter your data like in the example below. 

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.

You can try these examples for yourself using the sample datasets built directly into Prism. Just choose the 'entering mean (or median) and error values' tutorial dataset.