1. No less correct than the same text written in unconstrained English

2. More understandable than the same text written in unconstrained English

In my questionnaire, I would like to ask the participants comparative-style questions – such as whether the constrained text is (in their opinion) more/less correct/understandable than the unconstrained text. This type of questioning seems more appropriate given the hypothesis I am testing – however I am not clear on which statistical test to use with the comparative-style answers? Would the answers simply be giving me a ranking (i.e. 1 or 2) such that I could use the Mann-Whitney U test?

It seems like a more common approach would be to ask the participants to rate both the constrained and unconstrained text in terms of both correctness and understandability using some ordinal scale (e.g. 1-5). Since the results would (I think) be non-parametric, I understand I could use the Mann-Whitney U test to test each of my two hypotheses?

I would greatly appreciate some advice both on the design of my experiment and on the statistical test to use. I am a relative novice to statistics – so would greatly appreciate simple answers (or pointers to where I can learn more).

thanks,