Hi

I’ll be defending my thesis within the next three weeks.

I discovered a mistake in the way I collected part of the data during my experiment. It is a within subject experiment, where I asked users to use one interface under the first condition and to use interface B under the second condition. Instead of giving users a usability survey at the end of using each interface I gave them all the two surveys at end ( after they used interface a and interface B). I am worried that may have affect the results that I got and I am also worried that I might get a major correction or an MPhl.
I have not mentioned in my thesis when I have the survey to the user l, but the examiner may ask . And even if they did not ask I feel that I have to mention that and added it to my thesis.
Any advice? Has anyone came across similar mistak?