With our compromised immune systems, it's only natural to be more concerned about catching the flu. We quickly discover to our concern that predicting which flu variants will be the most common in the next flu season (so the right vaccine coverage is provided) and that even how prevalent the flu is are rather inexact sciences. So why can't the experts do better? Seems that the process is Stochastic, which according to the Oxford English Dictionary means that its a "pattern that may be analysed statistically but may not be predicted precisely.
Being stochastic doesn’t mean that there are no patterns or rules; it means that any individual outcome is subject to unpredictable effects.
Rules and randomness
Perhaps the simplest example of stochastic behaviour is tossing a coin. As you know, the two possible outcomes – heads or tails – are equally likely.
Toss this hypothetical coin 1,000 times and you should find that you count about 500 heads and 500 tails — a clear statistical trend. But try to predict the outcome of a single coin toss and you’ll have only a 50-50 chance of being correct. While there is a pattern in the long run, each individual coin toss is unpredictable."
So write University of Melbourne academics Rob Moss, Research Fellow, Mathematical Biology and Physiology, James McCaw, Associate Professor in Mathematical Biology and Jodie McVernon, Associate Professor, Population Health:
theconversation.com/why-pre...
Neil
Photo: After trying to wrap your head around that, you'd probably like to sit somewhere peaceful and just enjoy nature.
New Diagnosis :what does all this blood work mean? 
Coping With a CLL Diagnosis
A Reminder of the Symptoms of Shingles including the pre Rash phase. 
