The textbook by Mankiw.
The consumer price index is a single number that measures the overall cost of living, but it is based on thousands of prices for individual goods and services. To collect the raw data with which the index is constructed, hundreds of government workers go store to store every month. They check prices, write them down, and then send their reports into a central office, where the CPI is computed.
Explain please what the phrase 'go store' means. Maybe the government workers are officials whose duties are to check prices in shops and take account of them.