Science Buddies: "Ask an Expert"

Excel does not have a box and whisker plot. Where can I find a box and whisker plot that would allow me to make four box and whisker plots simultaneously on the same graph? I found a website, but it only makes one at a time (http://nlvm.usu.edu/en/nav/frames asid 200 g 3 t 5.html?open=instructions)

Bret,

I've never used (or reeded) software that will let you create a box and whisker plot, but I found a website that includes instructions on how to do it in Excel:

http://www.qualitydigest.com/oct97/html/excel.html
(scroll down to where it says "Box and Whisker Plots", or hit ctrl-f in your browser and type "whisker"; that will bring you to it)

There may be other (better) options out there, but this is what a quick search brought up, and should work for you.

(note: The article is from 1997, but will still probably work, as Excel is pretty backwards compatible)

Hope this helps,

Adam

Bret,

I assume that you are trying to compare the distributions of four different sets of data using a box and whisker plot. This is often referred to as a side-by-side boxplot. I am correct?

If I am correct, then there are many programs out there that will do what you need.

The first that comes to mind is the TI 83+, 84+, or 89 Titanium calculator. If you don't have one of these and you are a high school student, ask your math teacher because it is very likely that s/he or another teacher has one. I can provide you directions for generating the plots you need. The TI calculator is very user friendly, but its graphs are not super great, especially for visual display.

If you are fairly computer savvy, there is a GNU program called R (google search the R Project). R is also referred to as GNU S, and is a powerful statistical omputing tool that will make beautiful graphs for you. R, however, does lack a user-friendly GUI, but if you are comfortable with basic programming, you'll be fine.

You can also find Excel macros on the net for making boxplots. Try searching "Excel macro boxplot" on Google, and you wll find lots of options (though all with varying functionality and capabilities.)

The other options are programs like SYSTAT, MiniTab, S-PLUS, SPS, and other stats programs. These can get really pricy, but have superb graphing capabilities and a nice GUI. If your school has a statsitics class, they might have a copy or two of one of these programs. Another fairly basic (but very good) program is SigmaStat, which is manufactured by the makers of SYSTAT, but runs for only a few hundred dollars.

Other programs, like Origin, Mathematica, and Derive will also make nice graphs for you.


Here's the morale of the story: There are many programs out there that will make side-by-side boxplots. Some of them are free and some of them are pricy. Ask around at school and find out what options you have. Once you decide what types of resources are available to you, let me know and I can give you step-by-step guidance on the making of your plots.

"You can also find Excel macros on the net for making boxplots. Try searching "Excel macro boxplot" on Google, and you wll find lots of options (though all with varying functionality and capabilities.)"

I would avoid downloading macros from the internet, just because they can do a lot of harm if they are a virus. The instructions provided by awhite look straightforward, and there is no potential for mayhem.

I know OriginLab offers a free demo of Origin (a graphing program). When you print a graph it says "demo version" in light gray in the background... I don't know if that matters to you or not. Having used a number of scientific graphing programs I can say:
1) most of them do have a free trial you can download, tho they are disabled in some way (like only allowing a certain number of datasets to be added, or not saving)
2) they all are hard to use. You can make fantastic plots, but it takes a while to learn how to use them

If you can get excel to work using the website provided by awhite, that would probably be easiest.

If you make sure you use the same scale and boundaries on your axes you could do them all individually and then cut and paste onto the same poster board side by side.

Or you could do it the old fashioned way and use graph paper and draw them out yourself. The link that Adam provided shows how to do the formulas for calculating the quartile values and then you can plot them yourself.

best of luck,
Caroline

I often use Excel for boxplots. I find this procedure to be clear and simple, and it covers different versions of Excel:
http://www.mis.coventry.ac.uk/~nhunt/boxplot.htm

When I need a more complicated plot (e.g. boxes and whiskers that are located at uneven intervals, combination box and line plots etc), I set up a spreadsheet that calculates coordinates for the boxes and whiskers, and then plot those coordinates onto a x-y graph. If you want to try something like that, let me know and I can explain or post an example spreadsheet.

I have access to several statiscial programs, but for something like a box plot it is usually easier and more effective to make the plot in Excel.