Bio 270 Ecology
Making Bar Graphs in Prism
There are many routes and strategies to getting bar graphs made in Prism. As you use Prism more, you’ll
become facile at generating graphs in different ways – hopefully finding the most efficient in a given
situation. The instructions presented here assume you have already become familiar with Prism.
Prism is your friend approach – automatic graphing
Prism tries to be your friend and anticipate your graphing needs based on the form of the data set and the
analysis you might be doing. Frequently with column data, and especially if you are doing a comparative
analysis (e.g., t-tests, ANOVA) it will understand that you’ll want a bar graph, or x,y plot of the summary
statistics and make it automatically. If it is not what you wanted, use the Change; Graph type or Data
on graph options to get what you want. Bottom line- you need to know a priori what the graph you want
should look like.
One table one graph approach (good for small data file, quick graphing):
Make a data table for each graph that is formatted x= text for bar graph; y = mean, SD, (or SEM) n.
You then cut/paste or type in the relevant values from another table (e.g., Column Stats results).
One source table for descriptive stats, many graphs by selecting different data sets
(good for large data sets, many variables – e.g., acid data tables):
1. Open existing data table – single y columns of data, x= text.
2. Analyze; Data manipulations; transpose X and Y --- this will take a table with column format
and put the column headings in the x column, and the corresponding data in rows.
3. Analyze; Statistcal Analyses; Row means/totals --- in subsequent dialog, you can choose which
error measure you want (SD v SEM). This calculates the mean, error, and n for the data in each
row and returns a table in that format. All of the summary stats are in the same data set, however,
so it is not useful yet for graphing.
4. Make a new data table of format x=text for bar graphs, y = mean, SD or SEM, and n, and label the
data set columns (in Title space) for each variable. Name the data table.
5. Label the X column rows with the axis labels you will want for each treatment (e.g., Control, pH
3.5, pH 2)
6. Copy/Paste the relevant values into the y column for each variable to correspond to the treatment
from the Row means/totals results table.
7. To make a graph, go to Graphs; New graph, choose the data table you just produced, and select
the variable you want to graph. If the program has made a graph of all the variables, you can use
the Change; Data on graph option to delete all but one variable.
8. If you have multiple graphs to print out, use the Layout option to paste them all on one sheet.
Prism tricks and helpful hints