Related Experiment Video
Updated: Jun 5, 2026

Behavioral Assessment of Manual Dexterity in Non-Human Primates
Published on: November 11, 2011
Principal curve analysis avoids assumptions of dependence between measures of hand skill
Abstract:
The relationship between laterality and performance is unclear, and using laterality indices to explore this relationship can be misleading. An alternative approach is to consider laterality as a bivariate construct. A scatterplot of measures on each side will allow the distribution of values in a population to be visualised. However, determining where mean values lie in a population is problematic. Even nonparametric regression techniques such as lowess make assumptions about one variable being independent and the other dependent. Such assumptions are arbitrary in the case of measures by side. Assumptions of dependence are avoided using principal curve analysis. The results of two nonparametric fitting techniques (lowess regression and a principal curve analysis) are compared using hand skill data on 12,782 11-year-olds from a UK national birth cohort. The lowess regression is misleading. The principal curve analysis shows that absolute right-left performance differences increase with hand skill to a maximum about the point of average hand skill, and the difference is then constant up to extremes of hand skill.
Related Concept Videos
Curve Sketching and Derivatives
Guidelines for Sketching a Curve
Harmonic Mean
Take the example of the speed of a car, which is the measure of the rate of distance traveled. If the vehicle traverses the same distance back-and-forth, its average speed equals the total distance traveled divided by the total time taken. However, if the car moves with varying speeds, then the arithmetic mean is more skewed...
Degree of Curvature and Radius of Curvature
Actuarial Approach
Consider the example of a high-risk surgical procedure with significant early-stage mortality. A two-year clinical study is conducted,...
Calibration Curves: Linear Least Squares
For data that follow a straight line, the standard method for fitting is the linear...
