And no, i will not stop using the term ROI in this forum. What a silly thing to demand.
Masternode ROI is:
(Annual Reward + Capital Gain or Loss on the Collateral) as a percentage of the opening value (in dollars or other equivalent stable currency) of 1000 Dash.
It is not:
(Reward / Collateral)
You can continue to call it that if you like but it's extremely misleading at best and outright deception at worst.