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Thread by @michael_nielsen: ""The study failed to replicate" is something I often hear, usually with the implication the original study must have been bad, or had someth […]"

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"The study failed to replicate" is something I often hear, usually with the implication the original study must have been bad, or had something wrong with it.

This is a bad misunderstanding of what failure to replicate means.
An example: In 1995, Eric Cornell and Carl Wieman produced an amazing new form of matter, the world's first Bose-Einstein Condensate (BEC) (en.wikipedia.org/wiki/Bose%E2%8… ) They quickly won the Nobel Prize (2001) for this.
In 2000 I was visiting the laboratory of an atomic physicist. His main project was to produce BEC. He'd spent 4 years, perhaps 10,000 hours of staff time (including much of his own), & hundreds of thousands of dollars on this.

He'd seen absolutely nothing.
He was somewhat mournful about his failure to see BEC. But the lesson he drew wasn't that the original papers were wrong. It's that he still had more work to do.
I asked him what he thought was wrong.

"I don't know. I think it might be a problem with the power supply."

He described all the (many, many!) things he was doing to get cleaner current, as well as half a dozen other issues it might be.
Two years later I saw him again, a few months after he'd achieved BEC. I asked what had been the problem. "Turns out it was the power supply!" he said. Not quite beaming -- he's not a beamer -- but as close as he got.
Actually, when I dug down into details, he'd changed or fixed a _lot_ of things in the intervening two years. And it's hard to be sure. Maybe some of those other things were essential, too. Hard to test the counterfactual.
This type of story is very common. Often, failure to replicate means the experimentalist needs to do more work. The source of the trouble is often tacit knowledge or uncontrolled elements in the original paper.
This most emphatically doesn't mean the original paper is bad. Indeed, as with BEC, the original paper may be extremely good. Instead, it may mean more work is needed to understand exactly what's required to see the effect. The original paper is merely an important first step.
Another good example: measurements of the quality factor of sapphire (basically, how good a lasing substance is it) differed by _orders of magnitude(!)_ between Russia and the West during the cold war.
It took more than 20 years to sort this out! Turns out it was due to tacit knowledge available in the Russian lab that wasn't known in the West. Story is told here: orca.cf.ac.uk/71069/1/wrkgpa…
It's worth noting: some Western scientists thought this meant the Russian results were wrong. Turns out it was the Westerners who were wrong. (The Q of sapphire was a hot topic, as it was thought to be relevant for the detection of gravitational waves. So, not small stakes.)
A tempting response is to say "Oh, the paper should have included more detail." But first-rate experiments often include a mindboggling number of details that have to be gotten right. Figuring those out is (rightly) the decades-long task of an entire community doing followup work
If you don't believe this, look at the miniscule details Collins paper on the Q of sapphire. Or write out a list of all the possible noise sources in your power supply that might muck up an experiment. (I'll be waiting when your list passes 100 items.)
The "failure to replicate = bad" narrative is tempting. But it's a dramatic misunderstanding & oversimplification of how science works. I wish people had better mental models, to understand that failure to replicate is often instead merely a step along the way to understanding.
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