Monday, June 26, 2017

Understanding Randomness

Randomness is defined as the lack of a pattern in a series of events.  Since there is no pattern or apparent logic to the appearance, randomness allows for no predictability.  This may seem straightforward, but a poor understanding of randomness leads people to make untrustworthy decisions.

The lottery consists of a near-random selection of winning numbers.  In most big-money lotteries there are millions of combinations, so the odds of winning are much greater than a million to one against any individual player.  Suppose the numbers 5, 10, 15, 20, 25, 30 were drawn this week in a certain lottery.  Most people would not consider picking those numbers next week.  “What are the odds of the same numbers coming up two weeks in a row?” they would reason.  BUT because the numbers are chosen randomly, the odds of them coming up again next week are exactly the same as they were of coming up this week.  And the odds of those numbers coming up this week were exactly the same as the odds of any other combination.  To shy away from them because we have seen them so recently is not a sound strategy at all.

Everyone knows that if you flip a fair coin, it should come up heads about half the time and tails about half the time.  So if you flip a coin ten times in a row, most people would expect to see 5 heads and 5 tails.  BUT because the coin comes up randomly each time, the probability of getting 5 of each is only about one in four.  There is a three-times greater chance of getting some other combination.  The coin has no memory from one flip to the next.  It doesn’t know it’s supposed to come up one way or the other. 

In fact it is possible, but not very likely, that the coin could come up all heads.  Flip a coin ten thousand times and ten heads in a row somewhere in the sequence would not be that surprising at all.  It happens, but not very often.

Likewise, if a roulette wheel stops on red four times in a row, there is no logical reason to suppose it will not come up red the next time.  Seeing such a sequence, some people will bet on black, thinking it is “due.”  They will be rewarded for their “logic” about half the time and the rest of the time will remark on the weirdness of the situation.  BUT it’s not weird.  The roulette wheel is no more intelligent than the coin.

This identifying a pattern where there is none affects everyday decisions and beliefs.  When a single research experiment reveals that a certain food or other product is healthy or harmful, it could be true – assuming the experiment was carefully set up and carried out.  The finding could also be a random result – it just happened.  It takes others repeating the experiment and getting similar results, to show the findings were valid and not just some extraordinary fluke.

Unfortunately, it’s more exciting for scientists to do an original experiment and release the findings to the press with great fanfare, than to do the boring process of duplicating the work of others, especially when getting the same outcome will help those others take all the credit.  It might also be harder to get funding for a duplicate study.  We have to understand this to keep from over-reacting to the health news discovery-of-the-week.  So many people want to hang their hat on the results of a single study that just happened to confirm what they want to believe.

There are many other examples in our random world where we can be fooled either by apparent coincidences or by expecting patterns that don’t really exist.  But one important issue concerns self-medication, the pills, foods and experiences that each of us is sure make us feel better.  Most times, unless several researchers have done extensive studies, the improvement we feel is either coincidence or placebo.  Either we remember only the favorable outcomes or we put so much faith in the cure that our brains do the work.

When the folk medicine or sports superstition runs up against a ten-heads-in-a- row situation, we take it as truth rather than randomness and swear by it for the rest of our lives.

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