The total value of price reductions (not discounts or vouchers) of all product sold.
Formula
Price Reductions Value = SUMIF( Compare At Price IS BLANK, 0, Price - Compare At Price)
Price Reductions Rate = Price Reductions Value / Gross Merchandise Value
Explanation
Gross Merchandise Value is the sum of the RRP (Recommended Retail Price) of all items sold in a given period. Thus, it is before any deductions such as discounts, returns and taxes are made.
Due to that, it is not really a great measure of success as it can be easily inflated. It is still useful as a starting point in your P&L from which everything gets deducted.
Notes
We differentiate between Price Reductions & Discount Codes.
The Price Reductions Value shows if the price for an individual product was lowered - so if a Compare At Price was set. The Price Reduction does not include any additional reductions due to discount/voucher codes. These can be found in Discount Codes.
So, if a product used to cost €50 and you are now selling it for €40, then the Price Reduction Value ist €10.
The reason we differentiate between the two is that they usually have different purposes.
A discount a used to increase the sell-through of items that are not moving as quickly as anticipated whereas vouchers are mostly used by marketing to incentivize customers to buy.