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May 2017

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I wrote the following for another site (now defunct) a few years ago:

You are reading an article in your local paper reporting the findings of some recent research, which reports that the study revealed a link between eating some specific food and an increased risk of cancer.  Should you immediately remove that food from your diet?  How you respond to this information depends on how you interpret the findings, and properly interpreting the findings requires you to understand the relationship between correlation and causation.

Causation occurs when a first event *causes* a second event, while correlation is a broader term that only requires that the two events be related somehow.  While events that have a causal relationship will also be correlated, not every correlation is causal.  For example, the first and second event might *both* be the result of some unmeasured third event.  In the hypothetical example in the first paragraph, the specific food item might be associated with some independent activity that increases the cancer risk, so that merely eliminating the food will have no impact on the cancer risk.

A correlation finding is important in scientific research because it shows that there is some type of relationship between the variables.  These findings help show researchers where to focus further efforts to better understand the exact relationship.  The goal, of course, it to determine causation, but that conclusion can only be reached after carefully evaluating and eliminating the possibility of other types of relationships.

Unfortunately, the popular media tends to blur the lines in reporting these findings.  Where a scientific journal will normally be very specific in identifying the exact nature of the correlation, and will likely point out what further questions need to be answered to determine the nature of the correlation, the popular reporting tends to be a bit sloppy in describing the relationship described in the findings.  Combine this sloppy reporting with a general population that does not have a strong grasp of the relationship between correlation and causation, and people will conclude that the results show a causal relationship, even when that is not the case.  Having an awareness of this relationship allows a reader to analyze such an article critically, in an attempt to discern the exact nature of the relationship discovered.  This in turn, allows the reader to respond to the information in a more appropriate fashion.

I was thinking about this again recently because of all the posts I've been seeing on Facebook about the incident where Tim Tebow prayed over a spectator who was having a seizure.  The implication of these posts is that the seizure stopped *because* of Tebow's prayer.  People see the prayer and they see the seizure end, and they link the two causally.  However, just because the two events are correlated...this does not imply anything about whether one caused the other.  Except in very rare (and dangerous) situations, seizures end.  They are almost always self-limiting.  This persons seizure would have almost certainly have ended, even if Tebow hadn't been there. The end of the seizure can be explained by the medical sciences without any need to reference the prayer. There is no miracle here.  Is Tebow's prayer a genuine gesture of compassion? Only Tebow can say for sure what his motives were, but I'm inclined to take it as such.  Is there value in such gestures?  Certainly, in so far as they provide comfort for those involved and bind us a community.  Did it affect the medical outcome? Not at all.  I'm not opposed to prayer.  By all means, pray for the sick and others in need.  But don't expect those prayers to cure people or help those in need.  Don't *just* pray.  Let your prayers be accompanied by *action*.  DO something.  Get medical attention for the sick.  Lend a hand to those in need.  You need to be the instrument that answers your prayers.

A couple of weeks ago, there was a flurry of excitement when it was reported that “Russian SETI researchers are pursuing a promising signal”, as one headline put it.  It turns out that the hype was overblown, as it has been every time one of these stories has surfaced to date. While I haven’t seen that they’ve settled on a clear explanation for the signal they detected, the consensus is that it does not represent evidence of extraterrestrial intelligent life.  While that’s certainly disappointing to those, like me, who find the idea of life elsewhere in the universe fascinating, it shouldn’t be surprise.

I support the efforts of the Search for Extraterrestrial Intelligence (SETI), but I think I’m being realistic when I say that I don’t expect this effort to find any concrete evidence of any life elsewhere in my lifetime (and probably not in my daughter’s lifetime, either).  To understand why I don’t think it’s likely that we’ll detect such signals, let’s consider how signals propagate.  Isotropic signals propagate equally in all directions, so their signal strength is inversely proportional to the square of the distance from the source.  The random noise emitted by a technological society would be essentially isotropic, so that by the time the signal reached us, it would be incredibly weak, unless the signal was almost inconceivably powerful to begin with.  This is what is happening to all the radio noise we’ve been emitting into space for the last century or is propagating into space more-or-less equally in all directions, getting weaker at a rate that is related to the square of the distance from Earth.  However, signal strength can be improved by focussing signals in a specified direction.  The strength of such signals will decrease much less quickly than the isotropic signals, but there’s a catch.  The signal has to be directed almost directly at you for you to detect it.  In fact, the further away you are, the more precisely it must be aimed.  If we were to detect such a signal, it would either mean we had drifted across a signal intended for someone (something) else, or else that our presence was known.  Since our own signals have only propagated out for a bit more than a century, an intentional signal beamed back at us would almost certainly have to originate from less than about a hundred light years away.  There simply aren’t very many stars within that distance.

Even if, through some miracle, we did happen to detect a signal that clearly originated from an extraterrestrial source, the almost impossible to conceive distances of interstellar space raise all kinds of other problems.  Depending on how far away the signal source is from us, the civilization that created the signal could easily have disappeared since the signal was created.  A signal from a thousand light years away is going to take a thousand years to reach us.  It would not be a greeting from a current inhabitant of that point in space, but a time capsule of those who lived there back in time.  This limitation means that even if we detect such a signal, we have no ability, using our current knowledge and tools, to engage in any meaningful conversation.  And if there is life out there that has figured out how to overcome Einstein’s universal speed limit, we simply don’t know how to detect any message they might be transmitting.

Is there life out there?  There’s no way to know, at least so far.  Personally, I think it is likely, but I will readily admit that there is zero evidence to support that belief.  Would I be excited to hear that we’d discovered such evidence?  Absolutely.  Am I holding my breath in anticipation?  Ummm...not so much.

The human ability to recognize patterns is incredibly robust.  I have been observing the developments in the field of computer vision since 1990, and while the progress that has been made in programming computers to detect and recognize patterns has been impressive, the capabilities of the human brain in this area continues to elude the developers in this technology almost entirely.  Not only do humans have powerful, innate abilities to detect patterns with almost unbelievable speed, but our recognition accuracy is remarkably high.

However, it isn’t perfect.  One of the weaknesses we have in this area is the tendency to find patterns where none exist (the false positive result).  The relatively high false positive rate is a product of our evolution...a false negative (failing to see a pattern where one does exist) can have fatal consequences (such as not seeing a predator hiding in wait), whereas running from a danger that doesn’t actually exist is much less likely to kill someone.  As a result, over time, natural selection minimized our tendency towards false negatives, but did not particularly suppress any tendency to find false positives.

This tendency to see patterns even when no meaningful pattern really exists is easy to demonstrate.  We use it to amuse ourselves when we look for shapes in the clouds, and it is the reason we find the patterns we call constellations among the stars.  It is also probably a major factor in why so many people believe in conspiracy theories.  They find patterns in events, giving meaning to coincidences, even when there is, in reality, no underlying relationship between the events.  It seems that we have evolved to dislike randomness, with a strong preference for patterns, so much so that we will go to great lengths to find patterns everywhere.

This is why scientific inquiry requires experimentation.  When we think we’ve found a pattern, we use the alleged pattern to make a prediction, and then conduct an experiment to see if the prediction is correct.  If it isn’t, we may need to re-evaluate the data to see if the pattern actually exists or if it is just a product of our imagination.


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