Raleigh plot
Raleigh plots, also called circlegrams, are circular diagrams used to show directional data. They visualize a Raleigh test by mapping each observation as a unit vector around a circle and then averaging them to a mean vector. The length of this mean vector, r (ranging from 0 to 1), indicates how concentrated the directions are: r close to 1 means the directions are tightly clustered, while r near 0 means they’re spread out. The direction of the mean vector is the average direction.
In a Raleigh plot, the circumference shows angles (0° is often magnetic north, with angles measured clockwise). Each dot represents an observation, and the mean vector points to the average direction. You can display more than one mean vector to compare groups.
Raleigh plots are widely used in chronobiology to study biological clocks and orientation, such as monarch butterfly migration and how clock genes or proteins align with daily rhythms. They also help visualize how treatments or conditions shift the timing of peak activity. Beyond biology, Raleigh plots (or related circular plots) appear in geology for fault directions and in meteorology for wind directions (wind roses), as well as in cognitive psychology for responses to rhythmic stimuli. Variations of these plots visualize histogram-like data around the circle and emphasize dispersion.
In short, Raleigh plots turn circular data into a compact visual summary, making it easy to see whether observations cluster around a direction and to compare groups.
This page was last edited on 2 February 2026, at 03:34 (CET).