Studies are nice but they are just that, studies. It's been my experience that all the training in the world cannot prepare one for a particular incident unless, by some stroke of a magic wand, all the parameters of the training scenario are exactly reproduced and created in the real world. Training scenarios are usually replications of something that has happened in the real world so to train for such a situation means a duplication of a situation. What we, as intelligent beings have to do, is absorb all that training and be able to think on our feet. It's nice that we may know in passing what the statistics say about what drives a lunatic to do a mass shooting, what type of gun(s) he is bringing, etc. Again, not really helpful.
As a grunt in the jungle, I trained for nearly a year stateside before being deployed. All that training was nearly useless as the actual field experience taught me what to expect and full well knowing that nearly identical situations did not result in nearly identical actions, conclusions and results. Train like the BG is bringing an army. Prepare for the worst and bring your best game.
As a Federal Agent, training was intense and frequent. Simulations and range time were intense. However, in the field, I cannot recall one situation that was like a training scenario. Training gives you the basement of the building and your brains put up the rest of the structure while you are deep in the fire. Thinking under fire comes from experience. Not many of us have reached that plateau, thank goodness.
And with what seems to be a rash of mass shootings, be smart. If you are a CCW holder, make sure that gun is on you and be able to protect your family, friends, and innocent bystanders. Wouldn't you just love to see a headline that reads something like, "Bad guy intending to kill movie goers is taken out by a citizen with a legal gun and permit to carry it. Only injury is to the bad guy."