In its broadest sense, churn rate is a measure of the number of individuals or items moving into or out of a collection over a specific period of time.
The term is used in many contexts, but is most widely applied in business with respect to a contractual customer base. For instance, it is an important factor for any business with a subscriber-based service model, including mobile telephone networks and pay TV operators. The term is also used to refer to participant turnover in peer-to-peer networks.
The phrase is based on the English idiom "to churn up", meaning to agitate or produce violent motion..
The churn rate can be minimized by creating barriers which discourage customers to change suppliers (contractual binding periods, use of proprietary technology, unique business models, etc.), or through retention activities such as loyalty programs. It is possible to overstate the churn rate, as when a consumer drops the service but then restarts it within the same year. Thus, a clear distinction needs to be made between 'gross churn', the total number of absolute disconnections, and 'net churn', the overall loss of subscribers or members. The difference between the two measures is the number of new subscribers or members that have joined during the same period. Suppliers may find that if they offer a loss-leader "introductory special", it can lead to a higher churn rate and subscriber abuse, as some subscribers will sign on, let the service lapse, then sign on again to take continuous advantage of current specials.
Monthly and quarterly churn rates can also be calculated.
The attrition rate of licensed chiropractors in California: an exploratory ecological investigation of time-trend data.(Hypothesis)(Survey)
Aug 12, 2010; Authors: Stephen M Foreman (corresponding author) (equal contributor) ; Michael J Stahl (equal contributor)  Background A...