Today's military is a highly specialized and technical super-organism. Of course, the effectiveness of any military is dependent on its personnel; nevertheless, a modern military relies on advanced complex technology. The main focus of generalizbility theory involves quantifying the errors caused by individual components which are a part of the subject or system being studied.
Since operations involve the complex synergy of humans and a variety of specialized machines, the design, development and execution an action can only be served well by the implementations of test utilizing the theory. Where classical test theories work from a more idealized error assessment, generalizbility aligned testing can focus on specific facets of a particular error. Considering various personnel with various weapons and tools must be prepared for any number of differing geographic and climate conditions, generalizbility based testing provides a more detailed evaluation of the given data that can be applied towards specific solutions or situations.
The generalizability theory is a way of using a statistical framework to organize reliable observations. In other words, generalizability theory seeks to use current observations to predict future outcomes. Every action in the universe can be explained by a cause and effect relationship. Eating too much food will cause one to become fat. Therefore, if one can find the correct causes, one can also define the correct effects. Analysis of historical military campaigns shows that generals with effective information, planning, and logistics tend to win battles. What makes a general great, in fact, is their ability to generalize observations and make the best move possible based on the current situation. In conclusion, generalizability theory can be used to determine the actual effectiveness of military campaigns because of how they formalize the relationships between information on the battlefield to produce an effect, mimicking how a successful general would make his decisions.
Miltary conflict is complex and largely unpredictable. It is not simply about troop movements, but the unpredictable consequences of people acting under extreme stress, destroying infrastructure, sometimes in novel ways with new, unseen technologies. Furthermore, war involves complex political maneuvering and the interaction of economies and populations not directly involved. The unpredictability of it all has led to terms like the "fog of war" and makes it so that generalizability would not be able to adequately capture events as they unfolded in real time on the ground.
No, the generalizability theory cannot be used to determine the actual effectiveness of military operations, because military effectiveness depends on any given particular offensive. The army is not about who is the best at shooting in general; rather, the army is only as effective as the battle it is fighting.