Chained calculation

In the context of price indices, a chained calculation means a calculation is done one increment at a time and then multiplied to produce the index for the target date. The increment is usually a year. A chained calculation is in contrast to a fixed base calculation that calculates the target in one shot. In this sense a chained calculation is "path-dependent". The chained version of an index may require more data points (e.g. in the case of a Laspeyres index) in order to calculate an index for all years.

https://en.wikipedia.org/wiki/Price_index#Chained_vs_non-chained_calculations