A Systematic Review of Modifications and Validation Methods for the Extension of the Keystroke-Level Model

Table 3

Systematic review research questions and their motivations.

Research Questions	Motivation
RQ1: What was the purpose of extending the KLM?	Identify why the original KLM was modified, i.e., for which domain, application, or target user.
RQ2: What was the research method used to extend the KLM?	Identify research methods used to extend the original KLM, e.g., previous literature or user study.
RQ3: How was the original KLM extended?	Identify ways in which the original KLM was extended—specifically, how the operators and equations were affected. This includes, but is not limited to: original operators preserved, adapted or discarded, new operators and/or equations, updated M heuristics, and domain-specific metrics.
RQ4: What was the research method used to validate the extended KLM?	Identify research methods used to validate the extended KLM and the performance metrics utilised.