Directions for using SigmaPlot
Plot 1, Discrete Data

The directions for using SigmaPlot for this class will be cumulative, in that directions covered in previous plots will not be recovered in subsequent exercises. I will however, link back to previous directions. SigmaPlot is an extremely powerful package that you will also be able to use in other classes or when writing your thesis or other manuscripts.

To start SigmaPlot: Click on Start, then Programs, then SigmaPlot, then SigmaPlot 4.0. You will now come up with smaller window (entitled data) inside the larger SigmaPlot window.

To enter the data: In column 1, enter the numbers from 1 through 9. These will be the values for the number of species, which will be plotted on the x-axis. In column 2, enter the number of lakes that corresponds to the number of species. To label your columns (always very helpful when you look at this file days, weeks or even years later), put the pointer in the gray space above Column 1 and click on the right mouse button. This brings up a menu on screen and choose Column Titles. This brings up a box in which you can type in the column title for column one, click on Next to enter the title for column two. Choose Ok when done.

To create the graph: Click on Graph on the menu bar across the top, when the menu comes up, click on Create Graph. This brings up a box, in which you will choose the type of graph. From the list of Graph Types, choose Vertical Bar Graph. Then click on Next, and choose Simple Bar from the menu and choose Next. From this menu, choose XY Pair, then Next. The last menu picks the columns that contain the data. The menu should show X: species and then choose column 2 for Bar 1 by clicking on column 2. The menu should now read X: species and Bar 1: lakes. Then click on Finish. When you click on Finish, another window will appear that displays your graph.

Fine tuning: I will show you only a few of the control features in Sigma Plot. You are free to explore the many features of the program on your own and you can get much information from the help files. Click on Graph from the top menu bar, and then click on Graph Properties. In the graph properties window, click on the tab labeled Axes. There is a box labeled axis near the top and a button labeled Rename to the right of the small box. Click on Rename to rename the axis label. It now says Y Data. Change this to Number of Lakes in the text window and click on OK. You may notice that you can also change the font and its size in this window. Then choose X data in the axis box and change that title to Number of Species. To change the width of the bars, click on the Plots tab. On the left side on the window is a column labeled Settings For. Go down the menu until you find Widths and click on Widths; this brings up another menu, part of which is called Bar Thickness. To change the bar thickness drag the small arrow in one direction or the other. As this is a plot of discrete data, never set the bar thickness to 100% as this will remove the space between the bars.

To export the graph: Go to File on the menu bar at the top, and then to Export and save the file as a JPEG file. As a JPEG file, I could then put the file on the web page or I could import the graph into a variety of other programs.

To save your work: Go to File on the top menu bar, then Save As. This brings up the window for saving files. Make sure that the file will be save on the A:\ drive and then give it a name. You will be able to then retrieve your work and edit the data or the graph as you see fit.

Return to frequency distribution for discrete data.