Where does marginal collide?

In economics, marginal describes what happens with one additional unit: the extra cost, revenue, or satisfaction that comes from producing, selling, or consuming one more of something. The marginalist revolution of the early 1870s, marked by Jevons's 1871 The Theory of Political Economy, rebuilt value theory around choices made at the margin, holding that a price reflects the usefulness of the last unit rather than of the whole stock. Here marginal means incremental and forward looking, an amount added or removed at the edge of a quantity, and it has nothing to do with a probability summed over other variables, a person pushed to the edge of a society, or a note written beside a text.[1]

Unit

The change caused by one more unit, such as marginal cost or marginal utility

Recovery means

Not applicable

Measured by

Calculated as the derivative or difference of a total with respect to quantity, the change per added unit

In probability and statistics, a marginal distribution is the distribution of one variable, or a subset of variables, taken on its own, obtained by summing or integrating a joint distribution over all the other variables. The name comes from the margins of a two-way table, where the row and column totals sit; texts such as Casella and Berger's 2002 Statistical Inference define it against the joint distribution of every variable together and the conditional distribution of one variable given a fixed value of another. Here marginal means a total collapsed across everything else, a probability with the other variables averaged out, and it is unrelated to the effect of one more unit, a position on the edge of a society, or writing in a book's margins.[2]

Unit

The probability distribution of a subset of variables, the others summed out

Recovery means

Not applicable

Measured by

Obtained by summing a joint probability table over the unwanted variables, or integrating a joint density over them

In sociology, marginality is the condition of living on the edge of a social group or society, partly inside two worlds and fully at home in neither. Park's 1928 Human Migration and the Marginal Man named the marginal man as a person, often a migrant or someone of mixed heritage, who stands at the boundary of two cultures without full membership in either, and later work carried the idea into accounts of social exclusion and marginalized groups more broadly. Here marginal means peripheral and excluded, a place in a social order rather than a quantity, and it names neither an added unit, nor a probability summed over other variables, nor a note in the margin of a page.[3]

Unit

A person or group positioned at the edge of a social order

Recovery means

Movement toward the centre comes through fuller membership and belonging in a group

Measured by

Assessed through indicators of exclusion, such as limited participation, status, or access relative to a group's centre