Where does churn collide?

Customer churn is the rate at which customers end their relationship with a firm over a defined period, the attrition that erodes a subscription or contractual base and the exact complement of retention: churn prediction tries to estimate, for each customer, the probability of defecting so that the firm can intervene before they leave. Neslin, Gupta, Kamakura, Lu, and Mason's 2006 Defection detection ran a tournament of customer churn models and showed how much the choice of predictive method changes the profit of a churn management campaign. The referent is a loss process in a customer population, estimated with survival or classification models and counted as a defection rate, not a broker's trading, a two-phase flow regime, or the reshuffling of jobs.[1]

Unit

The fraction of customers who defect over a period, in percent, or a per-customer probability of churning

Recovery means

Churned customers can occasionally be won back through reactivation offers, but a lapsed subscription usually stays lost and costs more to regain than to keep

Measured by

Counted as the share of customers active at the start of a period who have left by its end, and modelled with hazard, survival, or classification methods that score each customer's churn risk

Churning, in securities regulation, is the excessive trading of a client's account by a broker who controls it, undertaken to generate commissions rather than to serve the client's interests: it is a recognised form of broker misconduct, established by showing that the broker controlled the account and traded it more heavily than the client's objectives warranted. Brown's 1996 Churning: Excessive trading in retail securities accounts analysed how the practice is defined and detected, including turnover-based tests of whether the trading in an account was excessive. The referent is a pattern of abusive transactions in one account, judged against the investor's goals, not a customer defection rate, a flow regime in a pipe, or the churning of jobs in a labour market.[2]

Unit

Trading volume relative to account equity, summarised by an annualised turnover ratio, weighed against the client's stated objectives

Recovery means

Not applicable

Measured by

Assessed from account records by turnover ratios and cost-to-equity or break-even ratios, together with evidence that the broker controlled the account

Churn flow is a chaotic, oscillatory regime of vertical gas-liquid two-phase flow that lies between slug flow and annular flow: as the gas rate rises, the ordered gas slugs of slug flow break down, and the liquid is churned up and down in an unstable, frothy motion with no stable interface. Taitel, Barnea, and Dukler's 1980 Modelling flow pattern transitions for steady upward gas-liquid flow in vertical tubes derived the mechanisms that bound each regime and placed churn flow as a transition on the flow-pattern map. The referent is a physical flow pattern in a pipe, identified by its phase distribution and superficial velocities, not a marketing metric, a broker's trading, or the turnover of jobs.[3]

Unit

A flow regime on a two-phase flow-pattern map, bounded by the gas and liquid superficial velocities

Recovery means

Not applicable

Measured by

Identified by visual observation, void-fraction fluctuation, or differential-pressure signals, and located on a flow-pattern map by the superficial gas and liquid velocities

Labour churning, or job churning, is the simultaneous creation and destruction of jobs, and the gross flows of workers hired and separated, that exceed what the net change in employment requires: an establishment that adds and loses posts at once, or replaces one worker with another, generates churn even when its headcount does not move. Burgess, Lane, and Stevens's 2000 Job flows, worker flows, and churning separated worker turnover into the part accounted for by job creation and destruction and the residual churning of workers through a stable set of jobs. The referent is gross reallocation in a labour market, measured as flows in excess of net employment change, not a customer defection rate, a broker's trading, or a flow regime in a pipe.[4]

Unit

Gross worker and job flows in excess of net employment change, expressed as a churning rate

Recovery means

Not applicable

Measured by

Computed from linked employer-employee or establishment data as gross worker flows minus the job reallocation implied by job creation and destruction