Which approach is least effective in retrieving a dog who has managed to slip off it's leash?*?

I believe the answer is: Running after the dog and shouting at it is not the best track of action.

When you run toward the dog while shouting, the dog might interpret is as you want to play with it, and its instinct is to run away from you. The more efficient method is to take out the dog's favourite snack and run away form the dog while holding it to make the dog chase you instead.

Running after the dog and shouting at it is not the best track of action. Chasing the dog will only cause the dog to become startled and continue to run away. To retrieve a wandering dog, run away from it.