One other note for today. Thinking about models is a skill in itself. I took this class online a few years ago and highly recommend it: https://www.coursera.org/learn/model-thinking It's free if you want and there is a pay option also. It starts Aug 8, 2016 so you may want to hop over there and check it out. It is not math or computer heavy - instead, it is an introduction to why we have models, how to use them and think about problems from a modeling point of view.
Questions, comments, concerns and criticisms always welcome,