Days of supply is a measure that indicates how long current inventory will last based on forecasted demand.
For this measure to be effective, it assumes that the forecast for the item usage is reasonably accurate. If the forecast is not accurate, the days of supply metric will not provide a reliable indication of how long the inventory will last. Other options like the correctness of the reorder point, the product life cycle phase, or the use of statistical process control (SPC) are relevant to inventory management but are not directly related to the accuracy needed for using days of supply as a measure.
References:
* Stevenson, W. J. (2018). Operations Management. McGraw-Hill Education.
* Chopra, S., & Meindl, P. (2016). Supply Chain Management: Strategy, Planning, and Operation.
Pearson.

Section: Fundamentals of Supply Chain Management
Explanation