Keystroke-Level Model

A simplified predictive model from human-computer interaction research, originally developed by Card, Moran, and Newell, that estimates task completion time by decomposing user interactions into elementary operations such as keystrokes, pointing movements, mouse clicks, and mental preparation time. In assistive technology, keystroke-level models are used to predict whether input aids like word prediction, scanning systems, or alternative keyboards will improve communication rate for a given user. The model helps quantify the trade-off between keystroke savings and the additional cognitive and motor costs of using assistive features.