Dr. Toru Nakata National Institute of Advanced Science and Technology, Japan. Nov. 20, Human Error — Theory and Prevention

Part I 2 Theory of Human Error Prevention

How we make mistakes 1-1 3

Why do we err? 4 Unknown Even masters of chess sometime commit easy mistakes. A lot of typical pattern of “misconception” are found. Four-card problem Monty Hall problem Horse Trading problem … But there is no universal tendency among them Change the question more productive. “Why can we usually avoid errors?” Because we can notice and fix errors before they break out.

Horse Trading Problem Frank sells Sue a horse for $60. Then he decides he wants it back, but Sue makes him pay $70 for it. Then Sue changes her mind and buys it back from Frank, but for $80 (Frank is no dummy). Finally, Frank buys it back from Sue for—you guessed it—$90 (Sue is no dummy, either). At this point, who comes out ahead? d=128 5

Typical Example of Human Error Accidents 1-2 6

Case 1: Confusing patients (1999, Japan) 7 Patient A: 74 yrs old. Plan to be undergone surgery on his heart. Patient B: 84 yrs old. Plan to be undergone surgery on his lung. Loaded an elevator together, Mistaken each other, when they brought out of the elevator. 7

But, it was doubtful… Some staffs in the operatin room said, “Is he patient A?” Different face, vital signs, etc Reconfirm by telephone to the patient room “Have Patient A been moved to the operation floor?” The answer was “yes” Yoshida Kenko, a famous author, said in his book “Tsure- zure-gusa”, The top secret skill of horse riding is “do not ride the horse, when you cannot convince the situation is perfect.” 8

9 Case 2: Bhopal accident (1984, India) Safeguards are not safe. Because, the management for safety becomes reluctant. Multiple Safeguards seem highly enough. In actual, all safeguard did not work enough. Not maintenance for them.

What is real meaning of Human Error?

Don’t say “error”, use term “uncertainty” 11 Is “error” wrong? Some errors bring good results at last. We cannot define “error” as a bad. What you are thinking is “uncertainty” in the work flow.

Three ability for human error prevention 12 AbilityMeaningPower Detectabilty/ Sensitivity against mistakes Can you (or work team) find hidden mistakes in the front of you? Only this ability can prevent the accident. Most important ability. Traceability for mistake Can you specify the cause of the mistake? Greatly reduce the cost to recovery. Secondary important. Dexterity Can you do your task without errors? Reduce running cost of the task. But no grantee for prevention of accident. (Even you are OK, other workers might sow seeds of accidents)

Part 2 13 Solutions for Human Error Prevention

Techniques to ensure human ability

Wake! 1) Fool-proof If the driver sleep, the train will stop automatically (Fig.1) 2) Fool-Trap If the driver violates speed limit, he will be injured before he hit somebody else. 15 Fig.2 Bump of the road. Fig. 1 Train console

Look your task! 3) Keep consious about your task. Sing work songs. “Cell Production system” 4) Comfortable weather People become thoughless when it is too hot or cold. 16 Boring line work Cell Production

Check with objectiveness 5) Use body and voice together Pointing and Calling 6) Check by pair “Pair programming” in software production. 17 Yes/No check Most easy and unreliable. Check with reporting number Check with argument

This is not end! 7. Prevent sense of achievement at too early timing Staffs are making a line when their task already finished. They think they have to keep their tension until this ceremony. 18

Tool and System to prevent human errors

Zoning No zoning Zoning for sanitary 20

Metaphor Tablet representing right to go forward Remove before flight strap representing the mode of door safeguard 21 Starbucks

Pop-out effect 22 Which is reverse? Is somebody there?

Planning the strategy

Event Tree Analysis (ETA) Mistake files Mistake buttons Business stops Mistake address Other Loose file Reek files Other 24 Ordinary problem Think risk of severe accidents from ordinary problem.

Fault Tree Analysis (FTA) Think the cause of a particular severe accident by asking why. shipwreck Titanic Lack of Boats No aids No rescue Iceberg Collision with other ships High sea 25 Paticular accident you have to prevent

How to gather incidents reports easily 26 WhenWhereWhatHowReactionWhoReview comment 9-2-Mon- 9:00Milling cutter No.3 DrillBrokenRenewalTanakaOK (Suzuki) 9-4-Wef- 13:00Heater No.5 IntakeDirtyCleanSatoTo be inspected (Suzuki ） 9-9-Mon- 10:03 Heater No.5 HolderScrew loosen TightTanakaOK (Suzuki) Easy to write in. Bring the data into Excel, and sort them. By sorting, you can find which features (when, where, ….) have got the most reports. That are the most dangerous features.

Slogan: “Safety by walking around” Hawthorne effect: Under the situation that somebody may watch your working scene, you tend to perform better, quicker, and safer. The watcher is NOT his boss. Without duty, people naturally try to show themselves as good workers. Walking around. Meet various staffs who are not bosses nor subordinates in order to encourage them. Negative Hawthorne effect: Under the situation that your supervisor is watching you closely, you fell uneasy and tend to refuse the observation. 27 Open Kitchen. The cook tend to perform better and more moderate, because somebody may watch him.