Resumen de Individual T2 Control Chart for Compositional Data
Maria Vives-Mestres, Josep Daunis Estadella, Josep Antoni Martín Fernández
The usual Hotelling T² control chart is not appropriate for monitoring processes where the quality characteristic is a mixture. The composition of mixtures are vectors of positive elements that represent parts of a whole, to which standard multivariate techniques are not appropriate due to their restricted sample space. There are many applications where a mixture is monitored against time, such as in the chemical industry, product composition, impurity profile, or gas components analysis. In this paper, a multivariate control chart for individual compositional observations based on the T² statistic is proposed and compared with the typical one in terms of average run length. The authors show how results are more consistent with compositional data nature and illustrate implementation in a real-world example.
