The National Bureau of Statistics released on February 11 the national Consumer Price Index (CPI) and Industrial Producer Price Index (PPI) data using 2025 as the base period, marking the first publication following the latest base period rotation. What is the purpose of conducting base period rotation for price indices? In response, an official from the Department of Urban Surveys of the National Bureau of Statistics stated that base period rotation is a fundamental task in the compilation of price indices and represents an international standard and common practice. It aims to adapt to new changes in the structure of goods and services transactions across production, distribution, and consumption sectors. The base period refers to the benchmark time against which price indices are compared, with the index set at 100 for that period. According to statistical regulations, China currently conducts base period rotation for CPI and PPI every five years. Starting in 2026, price indices using 2025 as the base period will be compiled and published. Taking CPI base period rotation as an example, CPI is a relative number that comprehensively reflects changes in the price levels of goods and services consumed by residents over a certain period. Since the categories and varieties of consumer goods are vast, a representative "fixed basket" of goods and services—commonly consumed, impactful on residents' lives, and representative—is selected to observe overall price changes. Their price movements represent the price changes of all goods and services in the economy. As economic and social development progresses, residents' consumption structure also changes, necessitating timely adjustments to the CPI survey's "fixed basket." For instance, with the increasing purchase of new energy vehicles in China, electricity for vehicles as an energy source for transportation must be promptly included in the CPI survey scope. CPI base period rotation involves adjusting both the "fixed basket" and the base period for price comparison to align with the latest changes in residents' consumption structure, thereby enhancing the representativeness of price indices and more accurately reflecting market price movements.