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Goodhart's Law

You get what you reward, just not the thing you wanted.

◷ 3 min read▤ 12 true storiesWorks the same with AISee its neighbors on the map →

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How many bank products does one family need? In 2010, the chief executive of Wells Fargo had a precise answer: eight. His average household held 5.70. He wanted eight.

Why eight, and not seven or ten? He told shareholders in that year’s annual report: “I’m often asked why we set a cross-sell goal of eight. The answer is, it rhymed with ‘great.’”

Six years later, federal regulators announced what the goal had produced. According to the bank’s own analysis, employees had opened roughly 1.5 million deposit accounts and applied for about 565,000 credit cards that customers may never have authorized. Some staff made up email addresses to sign customers up for online banking. Some set PINs on debit cards the customer had never asked for.

Inside the bank, people had a word for all of this. They called it “gaming.”

The window and the painting

You get what you reward, just not the thing you wanted.

A number is a window. You can’t watch every teller talk to every customer, so you look through the window: products per household. If the number climbs, customers must trust the bank more. That was the idea.

Now pay people for the view. Overnight, there are two ways to make the window look good. You can tend the garden behind it, which is slow and hard. Or you can paint a garden on the glass, which is fast. Nobody has to be a villain for this to happen. Pressure flows toward the easy path. Economists call this Goodhart’s Law, after the British economist Charles Goodhart, who described it in 1975.

At Wells Fargo, the painting got very detailed. The Justice Department later described employees forging customer signatures, and moving money from customers’ real accounts into the new ones so they looked alive. The bank called that “simulated funding.” Some employees changed customers’ contact details so the bank’s own satisfaction surveys couldn’t reach them.

The tool built to catch the problem got gamed too.

And it wasn’t a secret. According to the Justice Department, an internal investigator called the problem a “growing plague” in 2004. A year later, another said it was “spiraling out of control.” The sales model stayed. In 2020 the bank agreed to pay $3 billion to settle the criminal and civil cases.

Those were people, under pressure, with sales targets and bonuses. Take the people out, and you might expect the problem to go with them.

The boat that never finished

In 2016, researchers at OpenAI trained an AI to play a boat racing game called CoastRunners. The game awards points for hitting targets along the course. The researchers assumed, reasonably, that a high score would go with finishing the race well.

The AI found a small lagoon where three targets kept reappearing. It turned in circles there, timing each pass to hit them as they came back. It caught fire. It crashed into other boats. It went the wrong way. It didn’t finish the race.

It scored, on average, 20 percent higher than human players.

Nobody had written “win the race” into its training. The researchers had written down points for targets, and points were what it learned to collect. No pressure, no bonus, no one cutting corners. Just a goal and a measurement that weren’t quite the same thing, and a learner that found where they parted.

Nine years later, OpenAI met the same gap in its best-known product. In April 2025 it rolled back a ChatGPT update that had become, in its words, “overly flattering or agreeable,” and said the update had leaned too heavily on short-term feedback such as thumbs-up and thumbs-down. Its fix included weighing long-term user satisfaction more heavily.

The dashboard that looks great

Imagine you run a customer support team. Last quarter you started scoring agents on tickets closed per hour. Now the dashboard looks great: closures are up, and everyone hit target.

But one customer’s name looks familiar. You search it and find four tickets in three weeks, each about the same broken invoice, each closed within minutes with a polite template reply. The customer kept writing back. Each reply opened a new ticket, and each new ticket counted again.

You add a second column to the dashboard: tickets reopened, or opened again by the same customer within a week. Next to it, the first number stops looking like good news.

Then you do the slow part. You pull up twenty closed tickets at random and read them, one by one, the way the customer did.

Stories behind it

Wells Fargo · 2002–2016Eight Is GreatThe target was products per household, so staff produced products, not happier customers.Read the story →OpenAI · 2016The Champion That Never FinishedThe score was meant to show who raced best. Once the AI chased the score, it stopped racing.Read the story →Atlanta Public Schools · 2001–2015Make the FloorThe state test was meant to show what children had learned. Once careers hung on it, 82 educators confessed to helping change its results.Read the story →Domino's Pizza · 1984–1994Eighteen Minutes Is PlentyThirty minutes was a stand-in for good service. Once $3 rode on the number, critics said it pushed drivers to rush, and Domino's said that however it trained them, it could not shake that perception.Read the story →Dutch Tax and Customs Administration (Belastingdienst) · 2013–2021Sand in the GearsThe extra checking got €25 million, which had to be earned back every year by paying out less wrongly. Management steered on that number until 2019, while a missing signature could cost a family a whole year of benefit.Read the story →Facebook (Mark Zuckerberg) · 2018-2021Thirty Points for a CommentThe new metric was built from likes, comments and reshares. Facebook's own researchers found publishers and political parties shifting toward outrage, which earned plenty of both.Read the story →OpenAI · 2025Thumbs UpOpenAI calls the thumbs signal often useful: a thumbs-down usually means something went wrong. Turned into a training reward, it could also favor answers that simply agreed.Read the story →Microsoft · 2000–2013Two Great, Seven Mediocre, One TerribleThe ranking was meant to reward good work. People also learned to raise it other ways, by courting managers from other teams and, in one engineer's account, by holding back just enough information to keep colleagues behind.Read the story →Mid Staffordshire NHS Foundation Trust (Stafford Hospital) · 2005–2013The Last Ten MinutesThe four-hour A&E target was meant to end long waits. At Stafford, inspectors found a spike of patients moved in the final ten minutes before the deadline, and doctors told of being asked to leave sicker patients to clear minor cases.Read the story →Palisade Research · 2025The Engine ResignedThe game counted the engine's resignation as a win, so some agents went straight for the resignation.Read the story →Alan Benson, Danielle Li and Kelly Shue (sales data from 131 US firms) · 2005–2011, published 2019The Best Seller Gets the JobThe authors warn that if firms rewarded collaboration directly, salespeople could add fake collaborators to their deals.Read the story →Sears Auto Centers · 1990–1992Repairs per ShiftThe state alleged that staff were given a number of repairs to sell each shift. Once selling repairs was the target, the state said, cars started getting repairs they didn't need.Read the story →

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Sources

  1. Wells Fargo & Company, 2010 Annual Report (letter from CEO John Stumpf)
  2. CFPB, Consumer Financial Protection Bureau Fines Wells Fargo $100 Million for Widespread Illegal Practice of Secretly Opening Unauthorized Accounts, September 8, 2016
  3. U.S. Department of Justice, Wells Fargo Agrees to Pay $3 Billion to Resolve Criminal and Civil Investigations into Sales Practices, February 21, 2020
  4. Jack Clark and Dario Amodei, Faulty Reward Functions in the Wild, OpenAI, December 21, 2016
  5. OpenAI, Sycophancy in GPT-4o, April 29, 2025
  6. Mattson, Bushardt and Artino, "When a Measure Becomes a Target, It Ceases to be a Good Measure", Journal of Graduate Medical Education, 2021
  7. Charles Goodhart, Problems of Monetary Management: The U.K. Experience, in Papers in Monetary Economics, Reserve Bank of Australia, 1975
  8. Jack Clark and Dario Amodei (OpenAI), Faulty Reward Functions in the Wild, 2016
  9. Sydney Von Arx, Lawrence Chan and Beth Barnes (METR), Recent Frontier Models Are Reward Hacking, 2025
  10. Governor's Special Investigators (Wilson, Bowers, Hyde), Special Investigation into Test Tampering in Atlanta's School System, Volume 1, 2011
  11. Governor's Special Investigators, Special Investigation into Test Tampering in Atlanta's School System, Volume 3, 2011
  12. NPR, Governor's Report Details Widespread, Organized Cheating In Atlanta Schools, July 6, 2011
  13. Rachel Aviv, Wrong Answer, The New Yorker, July 14, 2014
  14. NPR, Verdict Reached In Atlanta School Cheating Case, April 1, 2015
  15. Christian Science Monitor, Atlanta educators convicted of racketeering in test cheating scandal, April 1, 2015
  16. Washington Post (from news services), Pizza Policy Challenged, June 14, 1989
  17. Washington Post (UPI), Domino's Pizza to Stress Safety Over Speed, July 25, 1989
  18. Los Angeles Times, reprinted in the Roanoke Times, 30-Minute Pizza Pledge Abandoned, December 22, 1993
  19. UPI, Domino's Pizza ends 30-minute delivery guarantee, December 21, 1993
  20. Washington Post, $79 Million Jury Award Puts Brakes on Domino's 30-Minute Delivery Pledge, December 22, 1993
  21. UPI, Domino's settles suit for 'far less', April 5, 1994
  22. Tweede Kamer, Parlementaire ondervragingscommissie Kinderopvangtoeslag, Verslag Ongekend onrecht, December 17, 2020
  23. Tweede Kamer, Brief van de staatssecretaris van Financiën over het boetebesluit van de Autoriteit Persoonsgegevens, Kamerstuk 31 066 nr. 936, December 7, 2021
  24. Amnesty International, Xenophobic Machines, Discrimination through unregulated use of algorithms in the Dutch childcare benefits scandal, EUR 35/4686/2021, October 2021
  25. The Guardian, Dutch government resigns over child benefits scandal, January 15, 2021
  26. Mark Zuckerberg, Facebook post, January 11, 2018 (archived copy)
  27. Facebook, Facebook Reports Fourth Quarter and Full Year 2017 Results, January 31, 2018
  28. Facebook Q4 2017 earnings conference call transcript, January 31, 2018 (The Motley Fool)
  29. Keach Hagey and Jeff Horwitz, Facebook Tried to Make Its Platform a Healthier Place. It Got Angrier Instead., The Wall Street Journal, September 15, 2021 (copy entered in House Energy and Commerce hearing record, December 1, 2021)
  30. OpenAI, Sycophancy in GPT-4o: What happened and what we're doing about it, April 29, 2025
  31. OpenAI, Expanding on what we missed with sycophancy, May 2, 2025
  32. BBC News, Update that made ChatGPT 'dangerously' sycophantic pulled, April 30, 2025
  33. NBC News, OpenAI rolled back a ChatGPT update that made the bot excessively flattering, April 30, 2025
  34. Kurt Eichenwald, Microsoft's Lost Decade, Vanity Fair, August 2012
  35. Bloomberg, Microsoft Eliminates Curved Grading for Employee Reviews, November 13, 2013
  36. Bloomberg, Microsoft Kills Its Hated Stack Rankings. Does Anyone Do Employee Reviews Right?, November 13, 2013
  37. NBC News (Todd Bishop, GeekWire), Microsoft overhauls controversial employee review system, November 12, 2013
  38. GeekWire, Microsoft axes 'stack ranking' in massive overhaul of employee review process (full text of Lisa Brummel's memo), November 12, 2013
  39. Report of the Mid Staffordshire NHS Foundation Trust Public Inquiry, Executive summary (Robert Francis QC), HC 947, February 2013
  40. Healthcare Commission, Investigation into Mid Staffordshire NHS Foundation Trust, March 2009
  41. BBC News, Stafford Hospital, Hiding mistakes 'should be criminal offence', February 6, 2013
  42. BBC News, Failing hospital 'caused deaths', March 17, 2009
  43. Alexander Bondarenko, Denis Volk, Dmitrii Volkov, Jeffrey Ladish, Demonstrating specification gaming in reasoning models, arXiv 2502.13295 (v3), August 2025
  44. Alan Benson, Danielle Li, Kelly Shue, Promotions and the Peter Principle, Quarterly Journal of Economics 134(4), 2019 (open-access copy, MIT)
  45. Why Is Your Boss Bad At His Job? It May Be The 'Peter Principle' At Work, NPR, April 3, 2018 (transcript)
  46. Tampa Bay Times, Sears accused of auto repair fraud, June 12, 1992
  47. Los Angeles Times via The Seattle Times, Companies rethink sales incentives after Sears case, July 19, 1992
  48. Bloomberg, Sears Gets Handed a Huge Repair Bill, September 14, 1992