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Cognitive Bias

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The Step Target Is Lower Than You Think

·1023 words·5 mins
The Step Target Is Lower Than You Think # In 16,741 older women, the mortality curve flattened at around 7,500 steps a day. The 10,000 figure everyone feels guilty about missing came from a 1960s pedometer’s product name — chosen partly because the Japanese character for 10,000 looks like a person walking. Where the real numbers sit # Lee et al. (2019, JAMA Internal Medicine) tracked 16,741 women with a mean age of 72. Two findings matter.

Taste Got Cheap, Insight Didn't

·673 words·4 mins
Taste Got Cheap, Insight Didn’t # We’ve shifted from buying what we need to buying what says something about us. Two things made that possible, and neither was a change in people — supply chains got cheap, and the internet started delivering taste to you whether you looked for it or not. How it happened # Global trade platforms made decent goods affordable, so quality stopped being a rich person’s problem. Then Instagram, TikTok and YouTube began handing you things you’d never have gone looking for. Between them, caring about materials and aesthetics became both easy and cheap.

The Two Horses Were Doing a Job

·681 words·4 mins
The Levi’s patch shows two horses tearing a pair of trousers apart. That isn’t decoration. In the 1870s many customers couldn’t read, so the claim — riveted, tougher than the cheap ones — had to be made in a picture. It worked. It’s still on your jeans. Logos used to be arguments # The good ones solved a specific problem for a specific audience.

Three Lenses, Three Different Questions

·955 words·5 mins
Fundamental, technical and macro analysis aren’t three competing answers to one question. They’re answers to three different questions — what is this worth, where is the price going, and what is the whole economy doing — and most arguments about which is “right” are people answering different questions at each other. What is it worth: fundamental analysis # The long-term owner’s lens. You’re not buying a ticker, you’re buying a share of a business, which means the job is working out what the business is worth and comparing that to what it costs today.

Your Valuation Is Wrong, So Demand a Discount

·979 words·5 mins
Every intrinsic value calculation you will ever do is wrong. That’s not a criticism of the method — it’s the reason the method includes a margin of safety. The discount isn’t caution. It’s an admission built into the arithmetic. What the number is trying to be # Buffett’s definition is unglamorous and precise: intrinsic value is the present value of the cash that can be taken out of a business during its remaining life. Three ideas packed into one sentence — all the future cash, when each piece of it arrives, and what that’s worth in today’s money.

Only the Limited Editions Are Investments

·691 words·4 mins
People buy a Montblanc telling themselves it’ll hold its value. Mostly it just doesn’t lose much, which is a different thing. The standard Meisterstück drifts up gently. The limited editions are where the actual money moved — and you can’t use those. The gap, in one pen # A 1992 Hemingway Writer’s Edition — built on the 149 but styled after its predecessor the 139, coral-orange barrel against dark brown — launched at roughly a tenth of what an unused one goes for now, somewhere in the $3,000 to $4,000 range.

The Fish Oil Evidence Is Messier Than Either Side Admits

·1000 words·5 mins
The Fish Oil Evidence Is Messier Than Either Side Admits # Two large randomised trials found standard-dose fish oil didn’t prevent heart attacks or strokes in healthy people. That’s the strongest argument against the capsule — and the popular follow-up claim, that it also causes atrial fibrillation, turns out to apply mainly to doses far above what’s in the bottle. What the big trials actually found # Two major randomised controlled trials tested standard-dose omega-3 against placebo — one following around 25,000 generally healthy adults, another around 15,000 people with diabetes. On heart attack, stroke and premature death, neither found meaningful benefit over placebo.

Your Wearable's Deep Sleep Number Is a Guess

·1055 words·5 mins
Your Wearable’s Deep Sleep Number Is a Guess # Wear four sleep trackers on the same night and they’ll agree on roughly how long you slept. On deep sleep — the metric people actually agonise over — one can report 47 minutes while another reports 81. Same body, same night, a 76% spread. What the devices agree on, and what they don’t # Total sleep duration is the reliable part. Across devices, total time asleep typically lands within about an hour of consensus, and for detecting sleep versus wake, validation studies put sensitivity at 95% or above for all major devices. If you want to know whether you slept six hours or eight, your wearable knows.

The Purchase Is the Cheap Part

·901 words·5 mins
Imagine someone gives you a Lamborghini. Free. You now owe five times the insurance, premium fuel, tyres priced like a holiday, servicing at $1,500–2,000 a year, and months of waiting whenever a part fails. The purchase price was the cheap part, and it was zero. Every luxury has a tail # That’s the general case. The sticker price is a one-off; what you’re really signing up for is a stream of obligations that shows up monthly, forever, and never appeared in the decision.

One of These Costs More Than the Other Seven

·1029 words·5 mins
Lists of things to stop buying treat every item as equally guilty. They aren’t. One purchase on the standard list costs more than all the others combined, and it’s the one people defend hardest. The car is the whole list # The average new car payment in the US hit $770 a month in the first quarter of 2026, an all-time high. Used runs $531. The average new loan is $43,925 at 6.39%, and used borrowers are paying 11.43%.

Most Blood Pressure Readings Are Wrong

·1093 words·6 mins
Most Blood Pressure Readings Are Wrong # A cuff two sizes too small adds nearly 20 mmHg. An unsupported arm adds almost 7. A full bladder adds 10 to 15. Stack a few of those and you have a diagnosis of hypertension manufactured entirely by technique. Why this matters in both directions # High blood pressure is the largest single contributor to strokes and heart attacks worldwide, and it produces no symptoms until it produces a catastrophe. That makes measurement genuinely important — and it makes measurement error important too, in both directions.

No Vegetable Unclogs Anything

·1132 words·6 mins
No Vegetable Unclogs Anything # Nothing you eat clears an artery the way a plumber clears a drain. But three categories of vegetable, eaten consistently for years, measurably slow arterial ageing, keep existing plaque more stable, and lower blood pressure in controlled trials. That’s a smaller claim and a far better supported one. Third: cruciferous vegetables # Broccoli, cauliflower, cabbage, kale, Brussels sprouts. People eating these regularly show less calcification and hardening in artery walls — the kind visible on an X-ray as faint parallel lines tracking a vessel, and conspicuously absent in people with healthy arteries.