Using Probability in Public Health Practice Think about what happens when you flip an ordinary coin one time. Can you predict with 100% accuracy what will happen? Of course not. But if you flipped that coin 100 times you would be pretty close if you had predicted the result would be tails 50 times and heads 50 times. If you perform the same experiment (flipping a coin for example) enough times, the actual outcome will approach the expected one based on the probability of each event. So, since you expect the probability of getting heads when flipping a typical coin is 50 percent, given enough flips heads will show up 50% of the time. This is a really great way of predicting outcomes when you are looking at a large number of trials or experiments. But what happens when you try to predict the outcome of a single trial? As you can see with the coin toss, it just does not work. Public health professionals make statements such as, “The United States’ 5-year survival rate for stage I breast cancer is 88%.” This number was calculated by looking at large numbers of women diagnosed with stage I breast cancer, then dividing the number of survivors at 5 years by the total number diagnosed. This number allows public health professionals to compare current rates in the US to rates in other countries or rates from previous years. It also allows comparisons to survival rates of other types of cancers; however, it does not allow professionals to predict a specific individual’s chance of survival for 5 years. To prepare: think about how the principles of probability can be applied both correctly and incorrectly in the practice of Public Health. By Day 4, post a description and original example of how probability is used in public health practice. Then, explain why using statistics and probabilities derived from a population (as is the practice in public health) could cause problems when applied to individuals in a clinical setting. Finally, differentiate between the focus of clinical practices, such as those of a therapist, pharmacist, RN, or MD, and the focus of public health practitioners. How can probability be applied in public health?