Length of Interview, Survey Duration or Survey Length
This is the amount of time it takes respondents to complete the survey.
The commonly used market research method for estimating survey duration is 3-4 questions per 1 minute. It should be noted that with grid questions, each row on the grid should be counted as an individual question.
Example: You have a grid with 10 rows - this equates to 10 questions and it is estimated that it will take a respondent approximately 2.5 - 3 minutes to complete it before moving on to the next survey question.