Methods of developing equations for objectively assigning or predicting an apparent age are disclosed. Advantageously, the equations of objective apparent age may be based on a relatively small number of critical parameters combined in a way that accounts for all or most of the apparent skin aging in a defined population or sub-population. Despite the relatively small data collection requirements, the present invention includes an objective model of apparent age that is useful for evaluation of products, useful for predicting treatment outcomes and useful for predicting the effects of deteriorative factors. The formalization of an Objective Apparent Age Score allows one to identify the biophysical and biochemical parameters that mostly influence an individual's apparent age, and can be used to select specific anti-aging treatments with increased chances of visible success. The Objective Apparent Age Score may also be used to support marketing claims.