First-order statistics of human stabilogram

Area of Science:

• Biomechanics
• Human Motor Control
• Statistical Analysis

Background:

• Quiet standing involves complex postural control mechanisms.
• The center of pressure (COP) is a key indicator of postural stability.
• Understanding COP statistical properties is crucial for assessing balance.

Purpose of the Study:

• To statistically model the center of pressure (COP) vector during quiet standing.
• To analyze the properties of COP deviations from the average.
• To identify factors influencing postural control variability.

Main Methods:

• Analysis of COP vector, locally averaged COP, and deviations from average COP using force platform data.
• Statistical examination of density functions and component correlations.
• Introduction of a new dimensionless quantity, average contrast.

Main Results:

• Observed indefinite multimodal distributions for COP components.
• Identified reproducible properties in deviations from averaged COP.
• Found correlated anterior-posterior and mediolateral deviation components with non-circular statistics.
• Discovered rotated main axes of equiprobability density curves.
• Identified two distinct subject populations based on statistical analysis.
• Observed both Gaussian and non-Gaussian distributions for COP deviation components, with non-Gaussian being more prevalent.
• Introduced average contrast as an indicator of non-Gaussian effects.

Conclusions:

• COP deviation statistics exhibit reproducible properties, offering insights into postural control.
• The average contrast is a valuable, calibration-independent indicator for assessing non-Gaussian effects in postural control.
• Statistical analysis reveals distinct patterns and populations within quiet standing behavior.