Here is my situaton. I have 50 edits, and then revisions made by 4 different editors. So imagine a dataset of 50 rows like this:

>EditNo, OrigEdit, Editor1Version, Editor2Version, Editor3Version, Editor4Version]

Now I want to conduct an experiment where each participant sees 10 random edits and each time is randomly assigned to see one of the editor versions, and then asked to rate edit quality on a scale of 1-5. 

What is the easiest way to do this? 

If I put this dataset into loop and merge I understand I can get a row each time but how do I also randomize which field (i.e: which editor) the user sees for that particular row.