Category: Graphical display

Category: Graphical display.. These links discuss some of the issues that you need to consider when displaying research data using a graph. Articles are arranged by date with the most recent entries at the top. You can find the theme and closely related categories, definitions, and other resources at the bottom of this page.

Stats: Stair step interpolation in R (November 15, 2007). I am working on some charts that show discrete (sudden) jumps at specific time points. This requires the use of stair step interpolation, because if you just connected the lines, it would imply a linear transition between consecutive points.

Stats: Patterns to look for in a histogram (September 21, 2007). When you plot your data in a histogram (or a stem and leaf diagram), you should look for patterns. Here are examples of three of the most important ones.

Stats: Colors for R graphs (June 28, 2006). I tend to use color sparingly in graphs because most of my graphs end up in black and white in the final production. Even on my web pages, which appear in color, I try to avoid too much use of color because I often print these pages on a black and white printer.

Stats: Graphics options in R (September 12, 2006). When you are producing graphics in R, the default option does not save your graphs for later review. You can change this in several ways. My comments will discuss the options for R running under Microsoft Windows. There are similar approaches that work for other systems.

Stats: Pitch the pie! Ban the bar! (June 5, 2003). This is an outline of a speech that I gave to Bluejacket Toastmasters on June 5, 2003. I work a lot with numbers and I've found that there is usually a good way to display those numbers and a bad way. Here's an example. It's a pie chart with bright bold colors and a deep 3-D effect. Is this a good way to display the data? WRONG! You should pitch the pie. Here's another example. It's a bar chart with big bold purple bars. Is this a good way to display the data? WRONG AGAIN! You should ban the bar.

Theme and closely related categories:

Definitions:

Other resources:

The 10 Commandments for Figures Excerpt: If you need to satisfy me because I'm your prof or you think I might be a referee, then just follow the rules. If you want more information about the rationale behind the rules, they are mainly based on the books by Edward Tufte which are really worth reading for the examples and interesting discussion.
2-D or not 2-D? (That is the question) Excerpt: We can learn how to be better presenters by observing the masters. I often say, for example, that we can improve our presentations by emulating certain aspects of Steve Jobs' presentation style. Today, though, I'd like to talk about one aspect of Steve's presentation Tuesday that we can learn from by not emulating. And that is the use of 3-D charts to represent 2-D data.
Interesting website: Data Visualization
Chart Burn: The "mountain charts" in fund ads can be confusing. Jason Zweig. Money 2000: 67-69.
Depicting Error. Howard Wainer. The American Statistician 1996: 50(2); 101-111.
How to interpret figures in reports of clinical trials. Description: This article reviews several commonly used data display methods and explains what a non-technical reader should look for.
Lightness Perception and Lightness Illusions. Edward H. Adelson. Accessed on 2003-10-13. ""Sometimes people think of illusions as failures of the visual system. However, they are usually caused by useful mechanisms that have been forced into an odd situation by a specially constructed stimulus. Without the underlying mechanisms, visual perception would not be possible. In normal life, the mechanisms work so smoothly that they are completely hidden. Through the use of illusions, we can reveal their action, and thereby study how normal vision works."" www-bcs.mit.edu/gaz/
Statistical graphics: mapping the pathways of science. H. Wainer, P. F. Velleman. Annu Rev Psychol 2001: 52305-35. [Medline]
Conventions for the graphical display of data. This link is broken. I last accessed the page on 2001-07-03. If anyone knows where this page has moved to, please let me know. "The purpose of this background report is to explain the codified role of data in the sciences and show how that affects the graphical presentation of data; by illustrating appropriate and inappropriate graphics I hope to heighten awareness of the ethical decisions faced by the creator of graphics." www.nmsu.edu/techprof/backgrnd/graphunit/graphback.htm

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This webpage was written by Steve Simon on 2007-08-06, edited by Steve Simon, and was last modified on 2008-07-14. Send feedback to ssimon at cmh dot edu or click on the email link at the top of the page.