Binning ensemble curves in vector coding analysis compounds information loss: Examples and recommendations

Vector coding is an analytical technique that quantifies relative motion by computing a coupling angle. Recently, it has become more common to bin the coupling angle such that it is categorized as in-phase, anti-phase, or component-dominant phase. However, the choice of whether to bin the pooled data (i.e., the full matrix of coupling angles) versus the ensemble curve (i.e., the mean coupling angle waveform) can profoundly influence the results. This paper highlights the effects of binning the pooled data versus the ensemble curve through conceptual and empirical examples. We demonstrate that binning the pooled data preserves valuable information regarding within- and between-cycle variability, while binning the ensemble curve can obscure this variability, leading to the mischaracterization of coordination patterns. Recommendations are provided to standardize binning procedures when conducting vector coding analysis.