Sorry for the slow response on this, but have been busy this week with a visiting scholar.

The original QJM was designed in the early 1970s as a "paper and pencil" system of analyzing combat. The research and dcoumentation that went into creating it are listed in the various HERO report that we offer through this website (see publications).

In 1977, Trevor N. Dupuy prepared a book that fully described the model at that time called "Numbers, Predictions, and War". This book is not currently in print but we do have eight copies left here and they are offered for sale (again see publications). That book fully describes the model as it existed in 1977.

Later, HERO/DMSI (Trevor N. Dupuy's company) created a computerized version of the model, originally in Basic, and later (around 1987/88) in Pascal. Also sometime during this process, a number of minor changes were made to the model that was incorporated into the program, but not in subsequent editions of the book. As such, the final version of the QJM differed in minor ways from the published version.

Around 1992, Trevor N. Dupuy undertook a wholesale revision of the model. While the basic concepts, and many of the tables in the model remained the same or similar, the model now used differential calculus to create Lanchester-like equations for helping to calculate the casualty exchanges. This work was done by Dr. James Taylor of the Naval Post-Graduate School. Furthermore, the methodology for scoring armor fighting vehicles was revised to better reflect modern development. Finally, a number of other small changes were made to modify and provide further fidelity to the model.

This revised model was called the Tactical Numerical Deterministic Model (TNDM), although it was a logical progression from the original QJM. It is fully documented, but this documentation is not publically available.

The model is owned by the Dupuy family (and others), and TDI serves as their representative. There is some detail provided on this model under the "TNDM and QJM" button.

If you look back to several posts I did on this site a year or so ago, you will see some detailed descriptions of some of the differences between the QJM and the TNDM.