Where does screening collide?

In information economics, screening is a procedure by which the party who lacks information gets the party who holds it to reveal what they privately know, by offering a set of choices designed so that different hidden types pick differently. Rothschild and Stiglitz's 1976 Equilibrium in Competitive Insurance Markets showed how an insurer, unable to see who is high risk, can offer a menu of contracts trading price against coverage so that each risk type sorts itself into a different policy. Here the uninformed side moves first and designs the test, which is the mirror image of signaling, where the informed side moves first to prove its quality. The referent is a mechanism for separating hidden human types through incentives, not a check for disease, a cloud of charge, or an evening at the cinema.[1]

Unit

One separating menu of contracts or tests that induces each hidden type to self-select

Recovery means

Not applicable

Measured by

Assessed by whether the offered choices produce a separating equilibrium in which types reveal themselves

In medicine and public health, screening is the testing of apparently healthy people who have no symptoms, in order to find a disease or a risk factor early enough to act on it. Wilson and Jungner's 1968 Principles and Practice of Screening for Disease, written for the World Health Organization, set out the conditions a screening programme should meet, including that the condition be important, that an accepted treatment exist, and that the test be acceptable, and Andermann and colleagues revisited those conditions for the genomic age in 2008. The practice is shadowed by biases such as lead time, where earlier detection lengthens apparent survival without changing the outcome, and overdiagnosis, where harmless conditions are found and treated. The referent is population testing of the well to catch illness early, not a way to sort hidden economic types, a shielding of charge in matter, or the projection of a film.[2][3]

Unit

One test applied to an asymptomatic person within a screening programme

Recovery means

Not applicable

Measured by

Evaluated by sensitivity, specificity, and predictive value, and by whether early detection improves outcomes net of lead-time and overdiagnosis biases

In physics, screening is the way a cloud of mobile charges gathers around a given charge and cancels much of its electric field at a distance, so that the charge appears weaker and shorter in reach than it would be in empty space. Debye and Hückel's 1923 Zur Theorie der Elektrolyte described this effect in an electrolyte and gave the characteristic distance, now called the Debye length, over which the field is damped out. The same idea governs how a charge is shielded inside a plasma or a metal. The referent is the physical damping of an electric field by surrounding charge, not a menu that sorts people, a medical test of the healthy, or a public film showing.[4]

Unit

The Debye length, the distance over which a charge's field is damped by surrounding charge

Recovery means

Not applicable

Measured by

Quantified by the Debye screening length computed from charge density and temperature, and probed through scattering and field measurements