When we notice two things change with each other — sunny days and ice cream sales, or player height and goals scored — it's natural to think that one thing is the cause of the other. And it's only a small step to consider that if you do more of one, you'll get more of the other. But this instinct and our natural sense-making behaviours can easily lead us astray. Just because two things change together — are correlated — doesn't mean that one causes the other: correlation is not causation.

You might reasonably notice a correlation between the number of children in a household and the number of storks nests on the roof of houses in Denmark or Holland. Fortunately, while the two may be correlated it's not hard to see that it's most likely not the storks that are causing the larger families and instead another factor such as the size of the house that is the more likely cause. As such it's a handy reminder that correlation is not causation.

This is also the subject of my favourite xkcd on correlation, and another on cell phones to drive the point home.

For more see the excellent spurious correlations.

The stork nest example is from Darrel Huff's How to Lie with Statistics, as is the example on Sampling Bias.

Correlation is not causation

An ode to the importance of little things.

This classic poem memorably paints a picture of how small details can matter, and how small changes can make a difference. Taking that extra bit of care, adding that extra bit of polish, helping that person when you had nothing to gain, showing up with generosity — all small actions that through their effect on others can, ultimately, have a large impact.

This same idea also applies to how we choose to spend our money and our time through contagious commerce — from Seth Godin:

While one person choosing not to eat meat will have a small impact on our climate, it will have a much bigger impact on the restaurants, groceries and food suppliers who notice what you’re doing.

They’ll change what they offer, and that will lead to a multiplier effect of other people changing their habits.

Buying an electric car or installing solar before they’re the obvious economic choice has the same impact. Because once marketers and investors discover that there’s a significant group that likes to go first, they’re far more likely to invest the time and energy to improve what’s already there...

...Very few people have the leverage to change the world. But all of us have the chance to change the people around us, and those actions change what gets built, funded and launched.

For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of horse the rider was lost.
For want of a rider the battle was lost.
For want of a battle the kingdom was lost.
And all for want of a nail.

For want of a nail

Whenever I find that I've accidentally written 'proceed' instead of 'carry on', 'affirmative' instead of 'yes', or 'convene' instead of 'meet' I try to remember Churchill's wise words:

"Short words are best and old words when short are the best of all."

Don't be like owl in Winnie the Pooh. Short, old words give power and clarity.

As an illustration of the remarkable power of Churchill's writing, I highly recommend the quick read of We Will All Go Down Fighting to the End, an eye-opening and stirring short collection of Winston Churchill's war speeches.

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Short words are best