Skip to main content

Table 4 Error in the length of the curve as a function of the number of points used

From: Comparison of geometric morphometric outline methods in the discrimination of age-related differences in feather shape

# 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%

  1. 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.