In an anatomic study, we suspect that our length measurement of an entity (1) is confounded by the length measurement of another entity (2). Entity 2, unlike variables such as age, smoking pack-year, etc. , has yet to be "stratified" into categories in the literature.
Before we attempt to make arbitrary categorization of entity 2, is there a way to disentangle the influence of entity 2 in the measurement of entity 1? Can this be performed through multiple linear regression?