base period

American  

noun

1. a period of time used as a standard of comparison in measuring changes in prices, taxes, income, etc., at other periods of time.

---

base period British  

noun

1. statistics a neutral period used as a standard for comparison in constructing an index to express a variable factor: 100 is usually taken as the index number for the variable in the base period

---

Example Sentences

Esper also said the pre-industrial period of 1850 to 1900 that scientists — especially the Intergovernmental Panel on Climate Change — use for the base period before warming may be a bit cooler than the instrumental records show.

From Seattle Times

After that, if unemployment in the state remains high, you may qualify for up to 13 more weeks, although to be eligible you need to have earned in your “base period” at least 40 times your weekly benefit amount.

From Los Angeles Times

P&G said Wednesday that organic sales in its home-care division rose in the low single digits last quarter even after a “high base period” a year ago when there was strong pandemic-driven demand for cleaning products.

From Washington Post

Kent-based Blue Origin, owned by Jeff Bezos, has been working directly with more than 20 companies in Washington state in support of its Human Landing System during the program’s “Base Period.”

From Seattle Times

Weekly benefit amounts are based on the wages paid during the base period, which must have exceeded $2,200.

From Washington Times