The Kirkpatrick Learning model helps with evaluating the effectiveness of training. It proposes evaluating at four levels:

  1. Reaction: What did learners think of the training
  2. Learning: Did learners improve their understanding or skill from before the training
  3. Behavior: Are learners applying the new/improved skill contextually
  4. Results: Have the organizational outcomes changed

Training design goes in the other direction, starting with the result, identifying the behaviors that need to change, and the learning needed to drive those behaviors.

My impression is that step 3 is the really tricky one. A lot of training interventions have a clear idea of the results they want, but don't do enough to consider what behavior change would be needed, and whether the environment actually supports that behavior. I suspect for most effective training the learning needs to be accompanied by environmental changes that incentivize the right behavior.