Biological systems, complex engineering analysis

Lubinski These are good questions, and Cronbach Meehl s (1955) treatment of construct validation is still a must read for people interested in these topics (but see also Meehl s recent refinements [personal communication, 1999]). Construct validity seeks to validate measures of a postulated attribute. Horsepower is a postulated attribute, you can t see horsepower, but you can construct indicators that co vary with meaningful criteria that reflect our concept of horsepower and make it a conceptually powerful and useful concept. Just as horsepower is an abstract property of complex combustion engines, g is an abstract property of complex biological systems. Moreover, constructs can be postulated intuitively, or inferred from families of empirical relationships, either is fine. In the final analysis what s important is, does the measure behave in accordance with our theoretical expectations about the postulated attribute it purports to assess Perhaps it would be helpful to review how Cronbach Meehl (1955) illustrated how construct validation works for psychological measures. 

The complex systems analysis of function of systems extends also to social systems. Perhaps it is better to consider that the field of complex systems does not create artificial distinctions between social, engineered, and biological systems. This is important when we consider the functional effectiveness (health) of the healthcare system in the same manner as we consider the functional effectiveness of a biological or engineered system. 

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