For many sports, coaches develop a game plan. Game plans are essentially theories developed to predict a win. That game plan/theory gets tested when players take the field or court. If the team loses, the game play/theory gets examined for why it failed, and perhaps tweaked for the next time. Businesses create marketing plans that are essentially theories that predict a certain set of actions will lead to success. For example, a theory that providing great customer service leads to repeat customers might result in increased training of the sales staff to be friendly and responsive. Again, the success of that theory gets tested and, in this instance, can actually be measured by increases in sales. Game plans and marketing plans are formally developed strategies for accomplishing a goal, but underlying them is some belief and acceptance of a particular theory. Such theories vary on several qualities such as their ability to accurately predict what will happen or the ability to actually test them. Within the sciences and social sciences, theories are evaluated for how well they explain or predict the world around us.