Business forecasting is not a pure science. It is more likely to be a matter of common sense, patience, research, and educated guessing than statistical analysis or higher mathematics. Consider the weather forecast: it’s one of the best forecasts available anywhere. Meteorologists study wind patterns, satellite pictures, air pressure, and years of past trends. Each forecast is based on careful analysis of what’s going on, why it’s going on, and why it might lead to something else tomorrow. If a storm is over the ocean and is headed toward the coast, then the probability of rain or sunshine is a professional guess, based on a wealth of knowledge, some good judgment, and common sense. Computers, satellites, and other tools increase the store of knowledge, but they can’t do it all alone. The same general idea applies to many other good forecasts. Market researchers, stock brokers, and even political analysts base their guesses on huge volumes of carefully analyzed information.…