Wednesday, January 16, 2008

Cycle plots for time series

In his most recent newsletter, Stephen Few from PerceptualEdge presents a short and interesting article on Cycle Plots (by Naomi Robbins). These are plots for visualizing time series, which enhance both cyclical and trend components of the series. Cycle plots were invented by Cleveland, Dunn, and Terpenning in 1978, and seem quite useful. I have not seen them integrated into any visualization tool, although they definitely are useful and easy to interpret. The closest implementation that I've seen (aside from creating them yourself or using one of the macros suggested in the article) is Spotfire DXP's hierarchies. A hierarchy enables one to define some time scales embedded within other time scales, such as "day within week within month within year". One can then plot the time series at any level of hierarchy, thereby supporting the visualization of trends and cycles at different time scales.

3 comments:

Naomi B. Robbins said...

Cycle plots, also called month plots, are available in both S-Plus (commercial software from Insightful Corporation) and R (open source software available at www.r-project.org). They are also available with Tableau Software, as mentioned in their blog at
http://www.tableausoftware.com/blog/building-cycle-charts-look-trend-data

DaveG said...

Hi,

which R package supports cycle plots?

This is surprisingly hard to find. EG with google & cran.

Dave

Naomi B. Robbins said...

Use the monthplot command. It's in the stats package which loads automatically.

Naomi