There are three common ways to establish probability: empirical, theoretical and expert opinion, oh and SWAGs. We have already started empirical with the concept of relative frequency. A table with relative frequencies is probabilities gathered from survey. As I looked over the data in the discussion board, it appears to me that the probability of encountering someone drinking 5 or less alcoholic beverages is much greater than the probability of encountering someone who drinking 15 or more drinks per week. Surveys are commonly used to gather such support for decision making in ambiguous environments. If I ask you the chances of getting heads on a coin toss (with a fair coin), you employ theoretical probability when you reason there are two outcomes possible each with an equal chance. Similarly if I ask what are the chances of drawing a heart from a well shuffled deck of cards? One in four or 25% Expert opinion is basically a matter of asking experts what they think the chances of some event are. If the expert has many thousands of hours of experience in the same predictable environment for which you ask the expert to opine, then yes their advice may be useful. Think of driving a car. Have you ever driven somewhere and not remembered driving there? Scary! That’s because you are an expert, unlike when you may have learned to drive a standard transmission car and likely suffered tremendous information overload in the middle of an intersection or on a hill… or worse an intersection on a hill, ha-ha. But if you are expert and driving in a predictable environment, you can rely on your expert opinion. BUT if something unpredictable happens (as may in the modern economy) … watch out! SWAG stands for scientific wild ass guess (as opposed to WAG which is just a wild ass guess). This has varying reliability, but is often used in many fields including economic and military analysis — two fields known for their great accuracy of predictions — kidding. Again SWAGs shrouded in clouds of impressive looking numbers and charts … like expert opinion may work for a while. They were instrumental in creating wealth up until the economic crash of 2008… then they let people down.