Table 4.

Error in the length of the curve as a function of the number of points used

# of Points	Mean error	Largest observed error
120	0.67%	1.14%
82	0.86%	1.54%
60	1.02%	1.67%
41	1.46%	2.43%
30	1.87%	2.95%
20	2.46%	3.55%

Initial digitization involved recording >200 arbitrarily space points along the periphery of the feather. Reduction of these points to a fixed number of equally spaced points (20 to 120) along the outline inevitably produced error. This error is expressed as a percentage of the total original length of the outline. The mean error is the average over all specimens in the study; the largest observed error is the largest over all specimens. Error increases as the number of points used to approximate the curve decreases.