Search and matching theory (economics)

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In economics, search and matching theory is a mathematical framework attempting to describe the formation of mutually beneficial relationships over time. It is closely related to stable matching theory.

Search and matching theory has been especially influential in

A matching function is a mathematical relationship that describes the formation of new relationships (also called 'matches') from unmatched agents of the appropriate types. For example, in the context of job formation, matching functions are sometimes assumed to have the following 'Cobb–Douglas' form:

${\displaystyle m_{t}\;=\;M(u_{t},v_{t})\;=\;\mu u_{t}^{a}v_{t}^{b}}$

where ${\displaystyle \,\mu \,}$, ${\displaystyle \,a\,}$, and ${\displaystyle \,b\,}$ are positive constants. In this equation, ${\displaystyle \,u_{t}\,}$ represents the number of unemployed job seekers in the economy at a given time ${\displaystyle \,t\,}$, and ${\displaystyle \,v_{t}\,}$ is the number of

${\displaystyle \,m_{t}\,}$

A matching function is in general analogous to a

${\displaystyle a+b\approx 1}$

If the fraction of jobs that separate (due to firing, quits, and so forth) from one period to the next is ${\displaystyle \,\delta \,}$, then to calculate the change in employment from one period to the next we must add the formation of new matches and subtract off the separation of old matches. A period may be treated as a week, a month, a quarter, or some other convenient period of time, depending on the data under consideration. (For simplicity, we are ignoring the entry of new workers into the labor force, and death or retirement of old workers, but these issues can be accounted for as well.) Suppose we write the number of workers employed in period ${\displaystyle \,t\,}$ as ${\displaystyle \,n_{t}=L_{t}-u_{t}\,}$, where ${\displaystyle \,L_{t}\,}$ is the

${\displaystyle \,t\,}$

${\displaystyle n_{t+1}\;=\mu u_{t}^{a}v_{t}^{b}+(1-\delta )n_{t}}$

For simplicity, many studies treat ${\displaystyle \,\delta \,}$ as a fixed constant. But the fraction of workers separating per period of time can be determined endogenously if we assume that the value of being matched varies over time for each worker-firm pair (due, for example, to changes in productivity).^[4]

Applications

Matching theory has been applied in many economic contexts, including:

• Formation of jobs, from unemployed workers and vacancies opened by firms^[1][4]
• Allocation of loans from banks to entrepreneurs^[5]
• The role of money in facilitating sales when sellers and buyers meet^[6]

Controversy

Matching theory has been widely accepted as one of the best available descriptions of the frictions in the

References