ABC of Response Process Validation and Face Validity Index Calculation

Validity evidence can be supported by five sources that are content, response process, internal structure, relation to other variables, and consequences. Response process validity measures the thought processes of users of the tested inventory as they respond to the assessment tool. These are commonly evaluated in the form of clarity of instructions and language used in the assessment tool, as well as the comprehension of instruction after training or an observation session. Response process validity contributes to the overall validity of an assessment tool; therefore, it should be quantified systematically based on the evidence and best practice. This paper describes a systematic approach to quantify response process validity in the form of face validity index based on the evidence.