In the mood for a “trick” question? The attached PDF uses a simple example to highlight the nuanced relationship between case reserves and estimates of IBNR for P&C insurance.
It is important to recognize that estimates of IBNR depend on case reserves. This means that there is an order-dependence when estimating total loss reserves.
First, case reserves (and other individual claim reserves) are estimated. Second, IBNR is estimated based on the case reserves and various other quantitative and qualitative elements.
Has the nuance described in the PDF created questions or confusion in your work?
Let me know if this post resonates.