10 Examples of Error Tolerance

John Spacey, May 02, 2017

Error tolerance is the design of things to be resilient to human error. The term is applied to user interfaces that are difficult to get wrong. When a human error does occur, error-tolerant designs gracefully detect and handle it. The following are examples of error tolerance.

Validation

Validating input to prevent mistakes. For example, preventing stock orders with a price that is too far from the market price such as a bid of $15 for a stock trading at $5.

Input Correction

Automatically suggesting a correction to input. For example, a search that makes a correction based on edit distance. The user is typically given a chance to override the suggestion to allow for unique input.

Input Flexibility

Systems that allow for a wide range of inputs to be understood. For example, a button with a generous touch target so that you don't have to touch it with precision to work. Voice commands may accept hundreds of variations of a single command.

Pokayoke

Constraints that prevent mistakes. For example, a battery unit that can not be installed incorrectly due to its shape.

Undo

The ability to undo actions or series of actions.

Shutdown

A machine that turns off if the user does something dangerous. For example, a camping heater that turns off if it is knocked over.

Friendly Errors

Telling the end user exactly what's wrong as opposed to a cryptic message or beep.

Clear Warnings

Warnings that are clear and direct. For example, an altitude warning in an aircraft that says "go up, go up, go up."

Authentication & Authorization

Systems of authentication and authorization such that people can't do things without a specifically granted permission. For example, a new employee who doesn't have system authority to accidentally delete your customer database.

Limits

Systems that enforce operational limits. For example, flight envelope protection that prevents a pilot from pushing an aircraft beyond its structural and aerodynamic limits.

Overview: Error Tolerance
Type	Human Error Design
Definition	The design of things to be resilient to human error.
Related Concepts	Fault Tolerance Pokayoke Human Error Safety Design Flight Envelope Protection Fail-safe Graceful Degradation