In an exchange with one of readers, he mentioned that about the possibility to quantifiably access the performances of armies and produce a ranking from best to worst. The exchange is here:
We have done some work on this, and are the people who have done the most extensive published work on this. Swedish researcher Niklas Zetterling in his book Normandy 1944: German Military Organization, Combat Power and Organizational Effectiveness also addresses this subject, as he has elsewhere, for example, an article in The International TNDM Newsletter, volume I, No. 6, pages 21-23 called “CEV Calculations in Italy, 1943.” It is here: http://www.dupuyinstitute.org/tdipub4.htm
When it came to measuring the differences in performance of armies, Martin van Creveld referenced Trevor Dupuy in his book Fighting Power: German and U.S. Army Performance, 1939-1945, pages 4-8.
What Trevor Dupuy has done is compare the performances of both overall forces and individual divisions based upon his Quantified Judgment Model (QJM). This was done in his book Numbers, Predictions and War: The Use of History to Evaluate and Predict the Outcome of Armed Conflict. I bring the readers attention to pages ix, 62-63, Chapter 7: Behavioral Variables in World War II (pages 95-110), Chapter 9: Reliably Representing the Arab-Israeli Wars (pages 118-139), and in particular page 135, and pages 163-165. It was also discussed in Understanding War: History and Theory of Combat, Chapter Ten: Relative Combat Effectiveness (pages 105-123).
I ended up dedicating four chapters in my book War by Numbers: Understanding Conventional Combat to the same issue. One of the problems with Trevor Dupuy’s approach is that you had to accept his combat model as a valid measurement of unit performance. This was a reach for many people, especially those who did not like his conclusions to start with. I choose to simply use the combined statistical comparisons of dozens of division-level engagements, which I think makes the case fairly convincingly without adding a construct to manipulate the data. If someone has a disagreement with my statistical compilations and the results and conclusions from it, I have yet to hear them. I would recommend looking at Chapter 4: Human Factors (pages 16-18), Chapter 5: Measuring Human Factors in Combat: Italy 1943-1944 (pages 19-31), Chapter 6: Measuring Human Factors in Combat: Ardennes and Kursk (pages 32-48), and Chapter 7: Measuring Human Factors in Combat: Modern Wars (pages 49-59).
Now, I did end up discussing Trevor Dupuy’s model in Chapter 19: Validation of the TNDM and showing the results of the historical validations we have done of his model, but the model was not otherwise used in any of the analysis done in the book.
But….what we (Dupuy and I) have done is a comparison between forces that opposed each other. It is a measurement of combat value relative to each other. It is not an absolute measurement that can be compared to other armies in different times and places. Trevor Dupuy toyed with this on page 165 of NPW, but this could only be done by assuming that combat effectiveness of the U.S. Army in WWII was the same as the Israeli Army in 1973.
Anyhow, it is probably impossible to come up with a valid performance measurement that would allow you to rank an army from best to worse. It is possible to come up with a comparative performance measurement of armies that have faced each other. This, I believe we have done, using different methodologies and different historical databases. I do believe it would be possible to then determine what the different factors are that make up this difference. I do believe it would be possible to assign values or weights to those factors. I believe this would be very useful to know, in light of the potential training and organizational value of this knowledge.