Halvor Mehlum

Mehlum, Halvor (2026). Price discrimination in a double horizontal differentiated duopoly market. Japanese Economic Review. ISSN 1352-4739. s. 1–19. doi: 10.1007/s42973-024-00184-3.

Mehlum, Halvor; Moene, Karl Ove & Østenstad, Gry Tengmark (2024). Add and rule. Journal of Economic Behavior and Organization. ISSN 0167-2681. 229. doi: 10.1016/j.jebo.2024.106852. 

Mehlum, Halvor; Natvik, Gisle James & Torvik, Ragnar (2024). The impossible trinity: Competitive markets, free entry, and efficiency. Journal of Public Economics. ISSN 0047-2727. 239, s. 1–12. doi: 10.1016/j.jpubeco.2024.105240.

Alpino, Matteo & Mehlum, Halvor (2022). Two notions of social capital. The Journal of mathematical sociology. ISSN 0022-250X. s. 1–28. doi: 10.1080/0022250X.2021.2004597.

Eva, Kløve & Mehlum, Halvor (2022). The self-enforcing dynamics of crime and protection. Journal of Peace Research. ISSN 0022-3433. 59(5), s. 742–755. doi: 10.1177/00223433211064801.

Mehlum, Halvor & Torvik, Ragnar (2021). The macroeconomics of COVID-19: a two-sector interpretation. Review of Keynesian Economics. ISSN 2049-5323. 9(2), s. 165–174. doi: 10.4337/roke.2021.02.01.

Mehlum, Halvor (2019). The polar confidence curve for a ratio. Econometric Reviews. ISSN 0747-4938. 39(3), s. 234–243. doi: 10.1080/07474938.2019.1580951. Fulltekst i vitenarkiv

Kløve, Eva & Mehlum, Halvor (2019). Positive illusions and the temptation to borrow. Oxford Economic Papers. ISSN 0030-7653. 71(3), s. 623–644. doi: 10.1093/oep/gpy050.

Mehlum, Halvor; Torvik, Ragnar & Valente, Simone (2016). The Savings Multiplier. Journal of Monetary Economics. ISSN 0304-3932. 83, s. 90–105. doi: 10.1016/j.jmoneco.2016.08.009.

Mehlum, Halvor & Østenstad, Gry Tengmark (2016). The political economy of migration policies in oil-rich Gulf countries. Oxford Economic Papers. ISSN 0030-7653. 68(4), s. 1062–1083. doi: 10.1093/oep/gpw033.

• Mehlum, Halvor; Moene, Karl Ove (Kalle) & Østenstad, Gry Tengmark (2024). Add and rule. Journal of Economic Behavior and Organization. ISSN 0167-2681. 229. doi: 10.1016/j.jebo.2024.106852. Fulltekst i vitenarkiv Vis sammendrag

  We suggest a new mechanism to explain political and economic inequality in resource rich countries. The mechanism is based on the premise that migrants are treated less generously in autocracies than in democracies. As a consequence, democracies want fewer migrants than autocracies. After democratization a new government may therefore start out with (potentially many) more migrants than their preferred level. These excess migrants, inherited from the autocracy, represent a costly legacy that makes democracy less attractive to citizens. With democracy less attractive, it is cheaper to compensate citizens for not challenging the autocratic regime. Not only that — by adding even more migrants, democratization becomes even less attractive, enabling the ruler to keep even more of the resource rents for himself without a threat of losing power.

• Mehlum, Halvor (2024). Price discrimination in a double horizontal differentiated duopoly market. Japanese Economic Review. ISSN 1352-4739. s. 1–19. doi: 10.1007/s42973-024-00184-3. Fulltekst i vitenarkiv Vis sammendrag

  Using a model of double horizontal differentiation, in which a variety dimension is added to a “linear city” duopoly model, I show that even when costs and demand are symmetric, price discrimination may be an equilibrium phenomenon. In the model, each customer has a preferred variety and a preferred firm. Customers have perfect information about all prices and may be induced to switch varieties and firms given a sufficient price difference. The price discrimination equilibrium exists when a sufficient subset of consumers are particularly price sensitive with respect both to variety and firm.

• Mehlum, Halvor; Natvik, Gisle James & Torvik, Ragnar (2024). The impossible trinity: Competitive markets, free entry, and efficiency. Journal of Public Economics. ISSN 0047-2727. 239, s. 1–12. doi: 10.1016/j.jpubeco.2024.105240. Fulltekst i vitenarkiv Vis sammendrag

  We present a model in which workers make occupational choices and vote over a tax rate which determines the level of government spending. Workers in occupations whose services are in high (low) demand by the government favor high (low) taxes. We show that the socially efficient size of the public sector cannot be supported in a political economic equilibrium. The reason is that equilibrium tax rates always reward excessive entry into the politically most powerful sector, and thus the equilibrium size of government is always either too big or too small. We show that this is an example of a more general political economy result that extends well beyond the baseline model and holds quite generally: the combination of (i) competitive markets and (ii) free entry is inconsistent with (iii) allocative efficiency.

• Mehlum, Halvor & Tomter, Håkon Andreas Dragesæt (2023). UTLÅNSFORSKRIFTEN. Samfunnsøkonomen. ISSN 1890-5250. s. 37–45. Fulltekst i vitenarkiv
• Alpino, Matteo & Mehlum, Halvor (2022). Two notions of social capital. The Journal of mathematical sociology. ISSN 0022-250X. s. 1–28. doi: 10.1080/0022250X.2021.2004597. Fulltekst i vitenarkiv Vis sammendrag

  We propose a model that reconciles two aspects of social capital: social capital as reciprocal sharing of favors within a selected group vs. social capital as trust that lubricates transactions in societies. The core assumption is that individuals have productive potentials, e.g., innovations, that can not be put at use autonomously. However, individuals can associate in a club to match productive innovator-implementor dyads among the members. For a given club, allowing one new member has the effect of a) an increased pool of innovations and b) an increased pool of potential implementers. Whether a particular member supports the expansion of the club depends on whether she expects to be an implementor or an innovator. When expansion of membership is decided by vote, both small exclusive clubs and open clubs encompassing the whole society can emerge. The outcome depends both on the voting protocol, on the distribution of innovator and implementer skills, and on the maximal potential club size. Moreover, identical environments may generate multiple equilibrium club sizes. In which of these the society ends up depends on the initial conditions and on the voting protocol.

• Eva, Kløve & Mehlum, Halvor (2022). The self-enforcing dynamics of crime and protection. Journal of Peace Research. ISSN 0022-3433. 59(5), s. 742–755. doi: 10.1177/00223433211064801. Fulltekst i vitenarkiv Vis sammendrag

  This article presents a model describing a symbiotic relationship between criminals and a partnership of protection providers, called the Firm. The partners of the Firm earn profits as they have market power in the supply of protection. The Firm recruits its new partners among criminals. As a result, the prospect of graduating to the Firm adds an incentive for violent crime. The result is a violence multiplier where more violence increases the profits to the partners of the Firm, in turn contributing to the incentive for violence. The violence multiplier also generates an incentive for the protection providers to welcome new partners, even though new partners dilute the profits. The model combines elements from contest theory and rent-seeking theory but, nevertheless, generates results that are in contrast to standard results from the rent-seeking literature. For example, due to the interdependence between protection providers and criminals, a decrease in the cost of violence increases violence more than pari passu and increases the value of being a criminal. Also, tougher competition between criminals may benefit all of them. The empirical relevance of key elements of this framework are confirmed by exploring unique data on incarcerated youth in South Africa. The empirical results confirm a hierarchical gang structure and indicate that this structure does indeed promote violence.

• Mehlum, Halvor (2021). Bevisvurdering. PrivIus Journal of Private Law. ISSN 2387-4538. s. 163–175. Fulltekst i vitenarkiv
• Mehlum, Halvor & Torvik, Ragnar (2021). The macroeconomics of COVID-19: a two-sector interpretation. Review of Keynesian Economics. ISSN 2049-5323. 9(2), s. 165–174. doi: 10.4337/roke.2021.02.01. Fulltekst i vitenarkiv
• Mehlum, Halvor & Torvik, Ragnar (2020). Etterspørsel og tilbud i koronaens tid. Samfunnsøkonomen. ISSN 1890-5250. s. 24–34. Fulltekst i vitenarkiv Vis sammendrag

  For vestlige markedsøkonomier er koronakrisen en ny type krise, men denne krisen har paralleller til økonomier til andre tider, og til kriser på andre steder. Vi skal her drøfte noen mekanismer fra tidligere makrolitteratur, og fra litteratur om makroøkonomi for utviklingsland, som inneholder økonomiske sammenhenger som over natten er blitt relevante også for vår økonomi. Fenomener som flaskehalser, rasjonering, tvungen sparing, innsatsvarebegrenset produksjon, likviditetsbegrenset produksjon, lønnsomhetsbegrensning, sektorheterogenitet, og kostnader som løper selv om produksjonen stenger ned, er alle permanente fenomener i utviklingsland men de dukker også opp i rike land i krisetider. I denne artikkelen vil vi presentere noen av disse grundig utviklete, men delvis glemte, mekanismene innenfor enkle læreboksbeskrivelser og gi noen eksempler på hvordan virkningene av finans- og pengepolitikk blir modifisert i en krisetid.

• Mehlum, Halvor; Torvik, Ragnar & Valente, Simone (2020). Growth with age-dependent preferences. Journal of International Trade and Economic Development. ISSN 0963-8199. doi: 10.1080/09638199.2020.1716834. Fulltekst i vitenarkiv Vis sammendrag

  We study the consequences of age-dependent preferences for economic growth and structural change in a two-sector model with overlapping generations and non-dimishing returns to capital. Savings and accumulation rates depend on the relative price of services consumed by old agents and on the intergenerational distribution of income. The feedback effects originating in preferences and income distribution yield three possible long-run growth outcomes: sustained endogenous growth, decumulation traps, and bounded accumulation. In the endogenous growth scenario, the transition features rising savings and accumulation rates accompanied by distributional shifts in favor of young workers, growing employment and rising prices in the service sector. Traps are triggered by initially low capital in manufacturing and low employment in services. Bounded accumulation yielding zero long-run growth in per capita incomes is induced by preferences, not by diminishing returns to capital.

• Mehlum, Halvor (2019). The polar confidence curve for a ratio. Econometric Reviews. ISSN 0747-4938. 39(3), s. 234–243. doi: 10.1080/07474938.2019.1580951. Fulltekst i vitenarkiv
• Kløve, Eva & Mehlum, Halvor (2019). Positive illusions and the temptation to borrow. Oxford Economic Papers. ISSN 0030-7653. 71(3), s. 623–644. doi: 10.1093/oep/gpy050. Fulltekst i vitenarkiv Vis sammendrag

  We provide an explanation of the low willingness to save that is observed in many developing countries. Our explanation is based on the hypothesis that people have an over-optimistic outlook. As discussed in the psychological literature, an illusionary positive view of the future may be a good thing. However, we show that it can lead individuals to accumulate unsustainable levels of debt. Using survey data from South Africa, we confirm that poor people are indeed overly optimistic, and that optimism is positively and significantly related to borrowing in general, and to expensive borrowing in particular.

• Mehlum, Halvor; Torvik, Ragnar & Valente, Simone (2017). Sparemultiplikatoren. Samfunnsøkonomen. ISSN 1890-5250. s. 51–53. Fulltekst i vitenarkiv
• Mehlum, Halvor; Torvik, Ragnar & Valente, Simone (2016). The Savings Multiplier. Journal of Monetary Economics. ISSN 0304-3932. 83, s. 90–105. doi: 10.1016/j.jmoneco.2016.08.009. Fulltekst i vitenarkiv
• Mehlum, Halvor; Moene, Karl Ove & Østenstad, Gry Tengmark (2016). Guest workers as a barrier to democratization in oil-rich countries. I Selvik, Kjetil & Utvik, Bjørn Olav (Red.), Oil States in the New Middle East: Uprisings and stability. Routledge. ISSN 9781138888340. s. 57–69. Fulltekst i vitenarkiv
• Mehlum, Halvor & Østenstad, Gry Tengmark (2016). The political economy of migration policies in oil-rich Gulf countries. Oxford Economic Papers. ISSN 0030-7653. 68(4), s. 1062–1083. doi: 10.1093/oep/gpw033. Fulltekst i vitenarkiv Vis sammendrag

  We study the political economy of migration policies in the oil-rich and non-democratic Gulf countries where different economic groups have divergent preferences over the migration policy choices. We consider two policy dimensions: a) the number of migrants allowed into the country and b) whether to discourage remittances by migrants. The inflow of migrant workers leads to a wage decline that harms citizen workers, while capitalists and oil rent earners benefit. When foreign exchange is remitted out of the economy, the real exchange rate depreciates. The remittance outflow benefits oil rent earners, while capitalists and workers lose. The autocratic ruler chooses a migration policy mix and an oil-rent redistribution scheme to maintain critical political support to avoid public rage. Our results explain differences in migration policies and redistribution schemes across Gulf countries. The model also offers predictions regarding the development of migration policies if these countries were to become more democratic.

• Mehlum, Halvor (2014). Stabiliseringspolitikk i krisetider. Samfunnsøkonomen. ISSN 1890-5250. 7, s. 16–24. Fulltekst i vitenarkiv
• Mehlum, Halvor (2013). Samfunnsøkonomiens plass i jussen. I Bull, Kirsti Strøm & Halvorsen, Marit (Red.), Det juridiske fakultet gjennom 200 år. Kontinuitet og fornyelse. Akademisk Publisering. ISSN 9788281520400. s. 87–104. Fulltekst i vitenarkiv
• Mehlum, Halvor; Moene, Karl Ove & Torvik, Ragnar (2012). Mineral rents and social development in Norway. I Hujo, Katja (Red.), Mineral rents and the financing of social policy. Palgrave Macmillan. ISSN 9780230370906. s. 155–184. doi: 10.1057/9780230370913.0013. Fulltekst i vitenarkiv
• Mehlum, Halvor (2012). Med Aukrust fra Norge til Hellas og tilbake. Samfunnsøkonomen. ISSN 1890-5250. Fulltekst i vitenarkiv
• Mehlum, Halvor & Moene, Karl Ove (2012). Aggressive elites and vulnerable entrepreneurs: Trust and cooperation in the shadow of conflict. I Skaperdas, Stergios & Garfinkel, Michelle (Red.), Oxford Handbook of the Economics of Peace and Conflict. Oxford University Press. ISSN 9780195392777. s. 706–729. doi: 10.1093/oxfordhb/9780195392777.013.0028. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Mehlum, Halvor (2022). Om sentralbanken i NRK Dagsrevyen. Fulltekst i vitenarkiv
• Mehlum, Halvor (2022). Pengepolitikk med Jens. Fulltekst i vitenarkiv
• Mehlum, Halvor (2022). Om sentralbanksjefen i NRK-nett. Fulltekst i vitenarkiv
• Mehlum, Halvor (2022). om streik i NRK-P1 dagens. Fulltekst i vitenarkiv
• Mehlum, Halvor (2022). Om Tusenfryd i NRK nyhetsmorgen. Fulltekst i vitenarkiv
• Mehlum, Halvor (2022). om streik i NRK nyhetsmorgen. Fulltekst i vitenarkiv
• Mehlum, Halvor (2022). TV2-nyhetene, Om Instituttet og Sentralbanksjef. Fulltekst i vitenarkiv
• Mehlum, Halvor (2021). Om Gardermoen i Amagasinet. Fulltekst i vitenarkiv
• Mehlum, Halvor (2021). Om formuesskatt i Aftenposten. Fulltekst i vitenarkiv
• Mehlum, Halvor (2021). Agenda podcast om koronaøkonomi. Fulltekst i vitenarkiv
• Mehlum, Halvor (2021). Coronaintervju Minerva. Fulltekst i vitenarkiv
• Mehlum, Halvor (2021). Om børsen i Klassekampen. Fulltekst i vitenarkiv
• Mehlum, Halvor (2020). Agenda podcast, Om koronaøkonomi. Fulltekst i vitenarkiv
• Davies, Rob; Mehlum, Halvor; Moene, Karl Ove (Kalle) & Torvik, Ragnar (2020). How the Zimbabweans pay for the war against covid-19. EDI COVID-19 ESSAY SERIES. Fulltekst i vitenarkiv
• Asheim, Geir Bjarne; Christiansen, Vidar; Hoel, Michael; Lund, Diderik; Mehlum, Halvor & Nyborg, Karine [Vis alle 8 forfattere av denne artikkelen] (2020). Subsidier til oljenæringen gir ikke omstilling. Fulltekst i vitenarkiv
• Mehlum, Halvor (2018). Om Nobellprisvinnerne 2018. Fulltekst i vitenarkiv
• Mehlum, Halvor (2018). Praktisk info. Om prisutvikling. [TV]. tv Norge. Fulltekst i vitenarkiv
• Mehlum, Halvor (2018). "Add and rule", Seminar University of Kent. Fulltekst i vitenarkiv
• Mehlum, Halvor (2018). Det strukturelle, oljekorrigerte underskuddet. Samfunnsøkonomen. ISSN 1890-5250. s. 15–19. Fulltekst i vitenarkiv
• Mehlum, Halvor (2018). The Sismondi principle. Fulltekst i vitenarkiv
• Mehlum, Halvor (2018). Om Nobellprisvinnerne 2018. Fulltekst i vitenarkiv
• Mehlum, Halvor (2018). Etter neste finanskrise. Fulltekst i vitenarkiv
• Mehlum, Halvor (2018). om statsbudsjettet, Dagsnytt. [Radio]. nrk , p1. Fulltekst i vitenarkiv
• Mehlum, Halvor (2017). Detektor om skattelette og olje. [TV]. nrk1. Fulltekst i vitenarkiv
• Mehlum, Halvor (2016). Fordelingen av gevinstene ved internasjonal handel. Fulltekst i vitenarkiv
• Mehlum, Halvor (2016). om Statoil og klima. [Radio]. NRK, dagsnytt 18. Fulltekst i vitenarkiv
• Mehlum, Halvor (2016). om makroøkonomisk krisehåndtering. Fulltekst i vitenarkiv
• Mehlum, Halvor (2016). Om Samfunnsøkonomi og Jus. Fulltekst i vitenarkiv
• Mehlum, Halvor (2016). Competition in space. Fulltekst i vitenarkiv
• Mehlum, Halvor (2016). Jobbe mindre for mer fritid? s. 56–57. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Anbefaler «grexit». [Journal]. Klassekampen. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Nye lån gir pusterom. [Journal]. Nationen. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). IMFs manipulering i Hellas. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Arendalsuka: Jobbskaping – hvordan kan norsk politikk gi flere jobber i fattige land? Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). NRK, Dagsnytt 18, Om Hellas og gjeld. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Kommentar til "Bør banker reddes?". Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). simmering conflicts. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Om makroøkonomisk krisehåndtering. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Bærekraftig velferd? Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Oljen i norsk økonomi. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Hva er bærekraftig velferd? Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Pengepolitikkens politiske økonomi. s. 54–55. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). From research to implementation: How can we use the knowledge to reduce capital flight from developing countries? Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Competition in Spacetime. A Theory of Sales. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Dutch disease. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Mer om folkeavstemning om gjeld i Hellas. [Radio]. NRK Dagsnytt 18. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Om folkeavstemning om gjeld i Hellas. [Radio]. NRK P1 Nyhetsmorgen. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Mer om euro og drakmer i Hellas. [Radio]. NRK Her og Nå. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Om folkeavstemning om gjeld i Hellas. [Radio]. NRK Dagsnytt 18. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Om euro og drakmer Hellas. [Radio]. NRK Her og Nå. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). Om folkeavstemning om gjeld i Hellas. [TV]. VG. Fulltekst i vitenarkiv
• Mehlum, Halvor (2015). NRK URIX, om Hellas. Fulltekst i vitenarkiv
• Mehlum, Halvor (2014). The resource curse. Publish what you Pay. Delegasjon fra Latinamerika. Fulltekst i vitenarkiv
• Mehlum, Halvor (2014). Informasjon om samfunnsøkonomi. Fulltekst i vitenarkiv
• Mehlum, Halvor (2014). Informasjon om samfunnsøkonomi. Fulltekst i vitenarkiv
• Mehlum, Halvor (2014). NRK p2, Dagsnytt 18. Om Argentinas betalingsproblemer. [Radio]. nrk p2. Fulltekst i vitenarkiv
• Mehlum, Halvor (2014). NRK P2 Dagsnytt 18 om Argentina. Fulltekst i vitenarkiv
• Mehlum, Halvor (2013). Europas økonomiske og politiske krise. Fulltekst i vitenarkiv
• Mehlum, Halvor (2013). Is it only the oil? Fulltekst i vitenarkiv
• Mehlum, Halvor (2013). Migration into resource rich Gulf economies. Fulltekst i vitenarkiv
• Mehlum, Halvor (2013). King of the Hill. Fulltekst i vitenarkiv
• Mehlum, Halvor (2013). The Firm. Fulltekst i vitenarkiv
• Mehlum, Halvor (2013). Europas krisehåndtering - når politiske og økonomiske krefter kommer i konflikt. Fulltekst i vitenarkiv
• Mehlum, Halvor (2013). Migration into resource rich Gulf economies. Fulltekst i vitenarkiv
• Mehlum, Halvor (2013). Ekko: Vekst eller ikke? [Radio]. NRK P2. Fulltekst i vitenarkiv
• Mehlum, Halvor (2012). Søndagsavisa: Om eurokrisa. [Radio]. NRK, P2. Fulltekst i vitenarkiv
• Mehlum, Halvor (2012). Dagsnytt 18. Om revidert nasjonalbudsjett. [Radio]. NRK, P2. Fulltekst i vitenarkiv
• Mehlum, Halvor (2012). Hellas’ hengende snøre. s. 4–4. Fulltekst i vitenarkiv
• Mehlum, Halvor (2012). Euroen og eurokrisen. Fulltekst i vitenarkiv
• Mehlum, Halvor (2012). Dagsrevyen 21. Om Hellas. [TV]. NRK1. Fulltekst i vitenarkiv
• Mehlum, Halvor (2012). Om nordisk samarbeid. Radioselskapet NRK p2. [Radio]. NRK p2. Fulltekst i vitenarkiv
• Mehlum, Halvor (2012). Om ressurser og konflikt, Ekko, NRK P2. [Radio]. NRK p2. Fulltekst i vitenarkiv
• Mehlum, Halvor; Natvik, Gisle James & Torvik, Ragnar (2021). The Inefficient Combination: Competitive Markets, Free Entry, and Democracy. Centre for Applied Macroeconomics and Commodity Prices (CAMP). Fulltekst i vitenarkiv Vis sammendrag

  We show that under fairly general conditions, the combination of (i) competitive markets, (ii) free entry, and (iii) democracy is inconsistent with allocative efficiency. This fundamental impossibility result, which has not been derived before, holds whenever not only prices, but also policy, responds to factor allocations. We develop a theory where agents enter an occupation (more generally, enter an economic activity) and thereafter make a policy decision. Thus, each voter's self interest becomes endogenous to the entry decision. In our baseline model, the policy instrument that citizens decide upon is simply taxation. Workers in occupations whose services are in high demand by the government have an incentive to vote for high taxes. Voters in occupations whose services are in low demand by the government have an incentive to vote for low taxes. We show that the socially efficient size of the public sector cannot be sustained in equilibrium, despite free entry into occupations. We generalize our theory, and show how our impossibility result extends well beyond the baseline model. We also discuss how departing from competitive markets may affect equilibrium outcomes. Our analysis implies that when assessing causes and consequences of factor allocations, it is key to acknowledge how allocations affect not only prices, but also policies.

• Mehlum, Halvor & Torvik, Ragnar (2020). Macroeconomics in the time of the Corona. Handelshøyskolen BI. Fulltekst i vitenarkiv Vis sammendrag

  For a developed market economies, the corona crisis is a new type of crisis, but this crisis has parallels to economies at other times, and to crises at other places. We discuss some mechanisms from the traditional macro literature, and from the literature on macroeconomics for developing countries, which contains economic mechanisms that overnight have also become more relevant to developed market economies. Phenomena such as bottlenecks, rationing, forced savings, production constrained by access to inputs, liquidity constraints, sector heterogeneity, and costs running despite production being shut down, are all permanent phenomena in developing countries. During the corona crisis, however, they have also emerged as key mechanisms in developed market economies. We discuss some of these well developed, but partially forgotten mechanisms, by extending simple textbook descriptions, and we provide some examples of how the effects of fiscal and monetary policy are modified in a time of crisis.

• Bratsberg, Bernt; Kotsadam, Andreas; Lind, Jo Thori; Mehlum, Halvor & Raaum, Oddbjørn (2019). Election Turnout Inequality Insights from Administrative Registers cesifo Working Paper no. 7465. cesifo. Fulltekst i vitenarkiv
• Mehlum, Halvor & Kløve, Eva (2017). The Firm and the self-enforcing dynamics of crime and protection. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  We model the symbiotic relationship between criminals and a part- nership of protection providers - the Firm. In the absence of state au- thority, insecurity and crime generate a demand for protection. When the protection providers themselves are recruited among criminals, the prospect of graduating to the Firm magnifies the incentive for violent crime. More violence in turn increases the income of the protection providers. The result is a violence multiplier. Combining elements from tournament and rent-seeking theory, we derive results that con- trast with standard results from the rent-seeking literature. For ex- ample, a decrease in the cost of violence increases violence more than pari passu and increases the value of being a criminal. The violence multiplier also generates an incentive for the protection providers to welcome new partners into the Firm. This is a crucial premise in explaining the viability of many violent structures. We confirm the empirical relevance of key elements of our framework by exploring unique data on incarcerated youth in South Africa.

• Mehlum, Halvor (2017). A polar confidence curve applied to Fieller’s ratios. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  I derive the polar representation of Fieller's estimation of confidence sets for ratios and construct a polar plot of the test statistics for all angles associated with the ratios. This procedure helps in visualizing and clarifying, but also systematizing, the features of the Fieller solution. In conclusion I discuss, using Ramanujan, the case where Fieller's method yields a confidence set covering the entire real line.

• Holtsmark, Katinka Kristine; Mehlum, Halvor & Ulltveit-Moe, Karen Helene (2015). Four essays on the dynamics of global public goods provision. Universitetet i Oslo. Fulltekst i vitenarkiv
• Græger, Nina; Austvik, Ole Gunnar; Holst, Cathrine; Mehlum, Halvor; Sand, Inger Johanne & Steinnes, Kristian (2012). Europa i endring - fase 2: 2013-17: Faglig og tematisk grunnlag. Norges forskningsråd. Fulltekst i vitenarkiv

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