Chapter 11: Efficiency Calculator
Use this chapter to compare scan costs across patterns and layouts.
Scan Distance Matters
Every item has a scan distance: the number of scan steps required to reach it. Reordering items so common targets have shorter distances can dramatically improve TER.
Practical Use
Use the calculator to compare layouts and see how many presses each pattern requires. This helps OTs choose a grid that balances speed and cognitive load.
Frequency vs Alphabetical Layout
Placing frequent letters early can halve scan time for common words.
Tip: Use frequency layout for communication grids unless there is a strong reason for alphabetical order.
Demo (Alphabetical vs Frequency)
🎮 Compare how quickly you can select common letters in each layout.
Alphabetical
Frequency
Efficiency is not only about scan rate. Layout, prediction, and error recovery often deliver larger gains than raw speed.