Keystroke-level model
In human–computer interaction, the keystroke-level model (KLM) predicts how long it will take an expert user to accomplish a routine task without errors using an interactive computer system. It was proposed by Stuart K. Card, Thomas P. Moran and Allen Newell in 1980 in the Communications of the ACM and published in their book The Psychology of Human-Computer Interaction in 1983, which is considered as a classic in the HCI field.