Updated: Jan 18
Almost 20 years ago, a high incidence of Firestone tire failures on Ford Explorers resulted in hundreds of deaths and thousands of catastrophic injuries. An investigation revealed that the tread on certain Firestone tire models was peeling off, resulting in tire failure. When the tires failed, the vehicles tended to roll over, sometimes killing the occupants.
This was perhaps the deadliest auto safety crisis in American history and resulted in a massive Firestone tire recall. A root cause analysis showed that one of the factors related to the tire failure was the process used to make the tires. Firestone used an assembly line system. When a worker saw a defect, they assumed that the problem would be taken care of somewhere else down the line. The line worker at the end might see an issue, but assume that if it were really a problem, someone would have noticed and made the change.
This can be explained by "diffusion of responsibility," a behavioral phenomenon where an individual is less likely to act on a need when others are present. It can also be explained by the closely related sociopsychological concept of "social proof" where an individual determines what is correct by finding out what other people think is correct. When an individual is uncertain about the correct action or behavior, they look to others to know how to behave. In the case of Firestone, each specialist had a limited scope of tire-making expertise that did not assume responsibility for other parts of tire making, the processes involved, or the desired quality. And even when someone had a broader understanding of the whole process and saw a problem, they felt inhibited by the fact that nobody else was reacting. If nobody else seems concerned about a problem, it makes it seem that there is not a problem.
Agile methodologies were designed to overcome these limitations. By creating hyper-collaborative teams around whole products and features, we create shared responsibility for an outcome, reduce the risk associated with the diffusion of responsibility, and significantly lower the overall risk that our product will have defects. This is particularly important when our products are a matter of life and death.