At the top of today’s episode, Dan shares an app that can help anyone struggling with integrating journaling into their routine like he was. The practice of writing out your thoughts, gratitude, goals, etc. each day is something done by some of the most successful people in the world. It does not come easily for some people though. Next we take a quiz on critical thinking, which is about asking the right questions, challenging assumptions, seeing more angles and being aware of thinking biases. Some really clever questions in this one!
1. A mother reads a scientific study that 17-year-old boys in the U.S. have fewer automobile accidents per 1,000 trips than 16-year-old boys. This prompts her to wait a year before letting her just 16-year-old son drive, to make him safer. Is her reasoning correct?
We don’t know if the driving improvement is due to 17-year-olds being more mature or due to them having on extra year of driving experience under their belts. If the latter, waiting a year won’t help. Probably both effects operate, so waiting may be wise. Lesson: Always consider multiple hypotheses when explaining a fact.
2. You play a game of tennis against a slightly better opponent and decide to put some money on the match. You are both equally fit in terms of stamina and physical endurance. Are your chances of winning the match the same whether you play just one set or the best out of three?
The longer you play, the more the final result will conform to the law of averages. Since this favors the better tennis player, your chances decline if you play three sets. If you were to play Roger Federer, say, your best chance to beat him is to play just one point and hope he misses. Lesson: Lay your bets according to the underlying statistics; consider base rates. The race may not always go to strongest or fastest, but that is nonetheless the way to bet.
3. Several studies about the benefit of bicycle helmets have shown that fewer severe head injuries occur – for most kind of falls or spills – if you are wearing a helmet. Does it follow therefore that making helmet use mandatory will further reduce head injuries in cycling?
Over the decades, helmet use has increased in the U.S. but head injuries did not decline as much as expect. Possible explanations include: improved bikes make riders go faster; wearing a helmet creates a false sense of security and more risk-taking on the road riders wear their helmets incorrectly; the type of people riding bikes may have shifted; traffic and road conditions may have changed. Experts especially blame the false sense of security that helmets give to bikers and car drivers. Lesson: Look for unintended consequences that may undermine your initial goal.
4. During the early part of World War II, many English bombers were being shot down by the Germans. To reduce their high casualty rate, the Royal Air Force decided to reinforce its bombers with armor. But where? Their statistical analysis of the bullet holes in planes that returned revealed a very uneven pattern of locations where planes had been hit. Should the RAF reinforce its bombers where bullet holes were most numerous, evenly throughout the plane, or elsewhere?
The initial thinking was to reinforce the areas with the most bullet holes. But when statistician Abraham Wald examined the surviving bombers for damage patterns, he came to a different conclusion. He reasoned that the surviving planes had not been damaged fatally by the random bullets and thus suggested reinforcing in places showing the fewest bullet holes. These were the most vulnerable, he argued, since few bombers apparently survived those bullet shots. The RAF followed his counter-intuitive advice and improved the survival rate of its bombers and crews. Lesson 7: Ask what data you aren’t seeing and why; there could be a selection bias, in this case known as a survivorship bias.
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