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Calculating “Death Rates” in the Context of Migration Journeys: Focus on the Central Mediterranean

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GMDAC Briefing Series: Towards safer migration in Africa: Migration and Data in Northern and Western Africa


  • More than 20,000 migrants have died trying to cross the Mediterranean since 2014.

  • The annual death toll has been falling in recent years; however, it is often argued that the “rate of migrant deaths” remains high, and that the risks that migrants face on their journeys have increased.

  • This briefing provides an overview of what factors to consider when calculating and interpreting such statistics and demonstrates how differences in the underlying data result in different mortality rates.

  • Calculating a mortality rate involves selecting a specific population, time period and points of comparison. However, in the context of irregular migration routes, calculating this figure is challenging for two main reasons: (1) the underlying data on deaths during migration and migration flows are highly incomplete, and (2) the choices made when making the calculation itself can significantly bias the final mortality rate figure.

  • The authors argue that it is often difficult to calculate the “rate of migrant deaths” accurately given the lack of reliable and complete data on migrant flows and fatalities. For example, the number of deaths may not be fully reported and data on the profile of persons on the move may be lacking. Some population groups, for example, might have a higher risk of death, such as children, and this might affect death rates when higher numbers of children are trying to cross borders.

  • How the population at risk of dying in the Central Mediterranean is defined can make a significant difference to mortality rate calculations. For example, if the population at risk is defined as the total number of people who arrived to Italy and Malta, as well as those who were intercepted at sea by Libya and Tunisia and the recorded fatalities at sea, the calculation of the mortality rate shows that in 2019, for every 21 people who attempted the Central Mediterranean Sea crossing, one person died (4.78%). However, if only the number of people who arrive in Italy and the recorded fatalities are used to calculate the population at risk, then the mortality rate was one death for every 13 people crossing to Europe over the Central Mediterranean (7.82%).

  • The authors conclude that it is important to make clear when presenting “migrant death rates” how such calculations are made. They suggest that such figures should be interpreted and used with caution, in-line with the limitations of the underlying data.