Where does rejection collide?

In statistical hypothesis testing, the rejection region is the set of possible sample results for which the null hypothesis is discarded rather than retained. Neyman and Pearson's 1933 On the problem of the most efficient tests of statistical hypotheses formalised this region, which they also called the critical region, and showed how to choose it so as to control the chance of a false rejection while maximising power against an alternative. A result that falls inside the region counts as evidence against the hypothesis at the chosen level. Here rejection is a decision rule defined over numbers, and it has nothing to do with an immune attack on a graft, a membrane holding back a solute, or a person fearing social exclusion.[1]

Unit

A decision outcome, reject or retain, fixed by whether a test statistic falls in the region

Recovery means

Not applicable

Measured by

Defined by a chosen significance level and a critical value or p-value threshold on a test statistic

In transplantation biology, rejection is the immune system's attack on tissue or an organ transferred from a genetically different donor, an attack that can destroy the graft. Medawar's 1944 The behaviour and fate of skin autografts and skin homografts in rabbits showed that a second graft from the same donor is destroyed faster than the first, establishing that the loss is an acquired immune response and not a simple failure to heal. Later work tied this response to donor antigens and to T cells. Here rejection is a biological reaction inside a living body, and it is unrelated to a decision rule in a statistical test, a membrane excluding a dissolved substance, or an emotional reaction to being left out.[2]

Unit

The immune-mediated failure of one transplanted graft in one recipient

Recovery means

Immunosuppressive drugs can slow or reverse an episode, but sensitised immune memory persists

Measured by

Detected by loss of graft function, biopsy grading of tissue damage, and donor-specific antibody or immune-cell assays

In membrane separation, rejection is the fraction of a dissolved substance that a membrane keeps out of the water that passes through it. Reid and Breton's 1959 Water and ion flow across cellulosic membranes reported that a cellulose acetate film could pass water while holding back salt ions, and Loeb and Sourirajan's 1963 asymmetric membrane made this practical for desalination. A rejection of one means the solute is fully blocked, and a rejection of zero means it passes freely. Here rejection is a physical exclusion ratio for a filter, distinct from a statistical decision rule, an immune attack on transplanted tissue, or a worry about being turned away by others.[3][4]

Unit

A dimensionless ratio from 0 to 1, one minus permeate concentration divided by feed concentration

Recovery means

Not applicable

Measured by

Computed from feed and permeate concentrations found by conductivity or chemical assay across the membrane

In social and personality psychology, rejection sensitivity is the tendency to anxiously expect, readily perceive, and strongly react to rejection by other people. Downey and Feldman's 1996 Implications of rejection sensitivity for intimate relationships introduced the construct and a questionnaire measure, and linked high sensitivity to distress and conflict in close relationships. People high in this trait tend to read ambiguous social cues as signs of being turned away. Here rejection names a pattern of expectation and reaction inside a person, not a rule for discarding a hypothesis, an immune assault on a graft, or a membrane holding back a solute.[5]

Unit

A trait score for one person, combining expected likelihood and anxiety about rejection across scenarios

Recovery means

Not applicable

Measured by

Assessed by the Rejection Sensitivity Questionnaire, which weights expected rejection by anxiety across hypothetical situations