Is it okay to use 'Don't know' or 'N/A' as an extra point(s) in a 7-point Likert scale?

I am using a 7-point Likert scale: strongly disagree to strongly agree. However, if the respondent doesn't know the answer, or if it is not applicable, I am hoping that instead of choosing the...

12 December 2018 2,217 4 View