Experimentation - the next step EDITED!!
To those who tried to follow my write up, my apologies. I have added a new comment further down in that post following alfanso's comments. I hope this gives an easier read than the original post. Also added a dropbox link to my spreadsheet.
If you had the patience to wade through the original post, thank you. It was hard to know how to write it up and with hindsight I should have gone with the dropbox link at the start. but, we live and learn, and I still have much to learn.