The role of mahalanobis space in quality engineering is to define the origin or the reference point in multi-variote space and the unit of distance. The distances of each n person including non-healthy people are used asn levels of signal. On the other hand, the new mahalanobis distances of the same n person by discarding some variales are output data to obtain Signal-to-noise ratio in order to judge the usefulness of the variable discarded.
A systematic way to select variables using an orthogonal array is also explained in this article.
