The proof of the promo--veinglory

Further the the question of what kind of promotions works well, I would like to suggest an experiment.
I am looking for authors with two back list books that sell a steady and similar amount. The idea is to pick one of those and promo the hell out of it during the month of May. Do your absolute minimum of promotion on the other (i.e. don't deliberately ignore it or remove it from your website or anything, but no active promotion). Keep some record of what promo you do.
At the end of June I will ask you to share your results. Note: I do not want to know your actual sale levels. Just calculate your average monthly sales for each book based on Dec-Jan (5 months). The tell me how many extra sales you saw for May.
For example, if the average for the promo book was 20 and in May you sold 25 your result would be +5. If the average for the control (non-promoted book) was 20 and in May you sold 15 your result would by -5.
I can do this and will focus on blog promo and maybe some banner ads. Who else thinks they could join in? Use any kind of book and any kind of promo you want. I would suggest either choosing a particular 1 or 2 types of promo
or taking a 'blitz' approach and doing everything you can think of. But please keep a record.