Three‐way clustering around latent variables approach with constraints on the configurations to facilitate interpretation

• Published in: Journal of chemometrics 2021-02, Vol.35 (2), p.n/a
• Main Authors: Cariou, Véronique, Alexandre‐Gouabau, Marie‐Cécile, Wilderjans, Tom F.
• Format: Article
• Language: English
• Subjects: Animal fat; Breast milk; Case studies; Clustering; CLV3W; Configurations; Constraint modelling; consumer segmentation; Data structures; Fatty acids; Globules; Life Sciences; Lipids; metabolomics; Methodology; Milk; nonnegativity; Oxidation; Parafac; Statistics; Variables; Weighting
• ISSN: 0886-9383; 1099-128X
• DOI: 10.1002/cem.3269

The set‐up of comprehensive studies in life sciences involving a longitudinal dimension—as appears in time‐scale metabolomics—calls for the use of dimension reduction techniques for three‐way data structures (e.g., samples by variables by time points). For this purpose, a clustering around latent variables for three‐way data approach, CLV3W, has been proposed. CLV3W aims at both partitioning the variables into nonoverlapping clusters and estimating within each cluster a rank‐one Parafac model consisting of a latent component (resp. a weighting system) associated with the first mode (resp. third mode) and a vector of loadings reflecting the degree of closeness of each variable of the second mode to its cluster. In this paper, two constrained CLV3W models are discussed. First, a nonnegativity constraint is defined implying that clusters are composed of positively correlated variables. Second, it is proposed to constrain the weighting system to be the same for all clusters. These two constraints aim at providing more parsimonious models with configurations that are easier to interpret. The appropriateness of both constraints is evaluated in a simulation study and illustrated on two case studies pertaining to sensory evaluation and metabolomics data. Regarding the first case study, CLV3W yields the identification of two consumer segments together with one common emotional pleasantness dimension associated with coffee aromas. CLV3W analysis of human preterm breast milk metabolomics data provided three clusters of lipid species that are responsible for specific functions (i.e., milk fat globules membrane‐constituents, fatty acid oxidation‐products, lipid mediators as eicosanoids and endocannabinoids). A clustering around latent variables for three‐way data (CLV3W) approach is presented. Constraints on the configuration aim at facilitating the interpretation of the CLV3W solutions. Nonnegativity constraint on loadings requires clusters with positively correlated variables only. Application of CLV3W to time‐scale metabolomics data provides a partitioning into consistent groups of bio‐markers.