The Geography of Worker-Firm Sorting: Drivers of Rising Colocation
Nils Torben Hollandt, Steffen Müller
IWH Discussion Papers,
No. 22,
2025
Abstract
Spatial segregation of low- and high-wage workers is a persistent economic issue with broad social implications. Using social security data and an AKM wage decomposition, this paper examines spatial wage inequality in West Germany. Spatial inequality in log wages rose sharply between 1998 and 2008, mainly due to increased variance in worker pay premiums across regions (48%) and stronger positive spatial assortative matching of workers and establishments (40%), i.e. colocation. Changes in establishment wage premia are mostly unrelated to rising colocation whereas labor mobility even reduced it. Instead, growth in worker pay premiums among stayers was concentrated in regions where high-wage workers and high-wage establishments were overrepresented already in the 1990s and, thus, magnified pre-existing colocation leading to ‘colocation without relocation’. Germany’s rising trade surplus, especially with Eastern Europe, boosted stayers’ worker pay premiums in those ex-ante high-wage regions and fully explains rising colocation.
Read article
The Contribution of Employer Changes to Aggregate Wage Mobility
Nils Torben Hollandt, Steffen Müller
Oxford Economic Papers,
Vol. 77 (2),
2025
Abstract
Wage mobility reduces the persistence of wage inequality. We develop a framework to quantify the contribution of employer-to-employer movers to aggregate wage mobility. Using three decades of German social security data, we find that inequality increased while aggregate wage mobility decreased. Employer-to-employer movers exhibit higher wage mobility, mainly due to changes in employer wage premia at job change. The massive structural changes following German unification temporarily led to a high number of movers, which in turn boosted aggregate wage mobility. Wage mobility is much lower at the bottom of the wage distribution, and the decline in aggregate wage mobility since the 1980s is concentrated there. The overall decline can be mostly attributed to a reduction in wage mobility per mover, which is due to a compositional shift toward lower-wage movers.
Read article
Media Response
Media Response February 2026 Oliver Holtemöller: Talsohle scheint erreicht in: Wirtschaftswoche, 13.02.2026 IWH: »Rosenkrieg« ums Arbeitszeugnis (Bericht mit Bezug auf…
See page
Archive
Media Response Archive 2021 2020 2019 2018 2017 2016 December 2021 IWH: Ausblick auf Wirtschaftsjahr 2022 in Sachsen mit Bezug auf IWH-Prognose zu Ostdeutschland: "Warum Sachsens…
See page
14th CompNet Annual Conference
14th CompNet Annual Conference 25-26 September, 2025 in Vilnius, Lithuania Programme Highlights – 14th CompNet Annual Conference, Vilnius, 25–26 September 2025 The conference…
See page
Research Articles
Research Articles Explore cutting-edge research based on CompNet’s micro-aggregated firm-level data and related analytical tools. These articles cover empirical and theoretical…
See page
Alumni
IWH Alumni The IWH maintains contact with its former employees worldwide. We involve our alumni in our work and keep them informed, for example, with a newsletter. We also plan…
See page
Alumni
Alumni IWH provides guidance and support in job placement after graduation, including letters of recommendation and career advice. Graduates have found placements in academia…
See page
The Contribution of Employer Changes to Aggregate Wage Mobility
Nils Torben Hollandt, Steffen Müller
Abstract
Wage mobility reduces the persistence of wage inequality. We develop a framework to quantify the contribution of employer-to-employer movers to aggregate wage mobility. Using three decades of German social security data, we find that inequality increased while aggregate wage mobility decreased. Employer-to-employer movers exhibit higher wage mobility, mainly due to changes in employer wage premia at job change. The massive structural changes following German unification temporarily led to a high number of movers, which in turn boosted aggregate wage mobility. Wage mobility is much lower at the bottom of the wage distribution, and the decline in aggregate wage mobility since the 1980s is concentrated there. The overall decline can be mostly attributed to a reduction in wage mobility per mover, which is due to a compositional shift toward lower-wage movers.
Read article
Trade Shocks, Labour Markets and Migration in the First Globalisation
Richard Bräuer, Felix Kersting
Economic Journal,
Vol. 134 (657),
2024
Abstract
This paper studies the economic and political effects of a large trade shock in agriculture—the grain invasion from the Americas—in Prussia during the first globalisation (1870–913). We show that this shock led to a decline in the employment rate and overall income. However, we do not observe declining per capita income and political polarisation, which we explain by a strong migration response. Our results suggest that the negative and persistent effects of trade shocks we see today are not a universal feature of globalisation, but depend on labour mobility. For our analysis, we digitise data from Prussian industrial and agricultural censuses on the county level and combine them with national trade data at the product level. We exploit the cross-regional variation in cultivated crops within Prussia and instrument with Italian and United States trade data to isolate exogenous variation.
Read article