Shifting baseline
A shifting baseline (also known as sliding baseline) is a type of change to how a system is measured, usually against previous reference points (baselines), which themselves may represent significant changes from an even earlier state of the system.
A conceptual metaphor for a shifting baseline is the price of coffee. A cup of coffee may have only cost a $0.05 in the 1950s, but in the 1980s the cost shifted to $1.00 (ignoring inflation). The current (21st century) coffee prices are based on the 1980s model, rather than the 1950s model. The point of reference moved.