As experts on migration we should be able to answer the core question in our field: why do people migrate? But the question defies simple answers. People and places are diverse, and the things we know the most about are not necessarily the ones that are most important.
A breakthrough in trying to answer the question lies in splitting in in two. First, what makes people want to migrate? And second, what makes it possible to convert this wish into actual migration? The two are not the same. For instance, poverty might spur a wish to leave, but but being poor doesn’t make it easier to overcome the obstacles to moving to another country. In migration research, such two-step approaches improve our understanding.
Over the past couple of decades, thousands of people have responded to surveys with questions about wishing or planning to migrate. Researchers have analyzed the data to identify the drivers. Are people seeking to escape crime, or trying to flee their own unhappiness? Are prospective migrants put off by discrimination at the destination? Or does a wish to migrate reflect an adventurous personality? Individual studies have sought to answer such questions. But until now, nobody has systematically pieced together the big picture of what makes people want to migrate.
Together with my colleagues Maryam Aslany, Mathilde B. Mjelva and Tone Sommerfelt, I have spent months poring over studies that examine the determinants of migration aspirations. In line with much migration theory, we use ‘migration aspirations’ as an umbrella term for desires, hopes, intentions or plans for migration. These words describe thoughts and feelings that differ in important ways, with consequences for how it makes sense to ask questions in surveys. But, for now, we put the differences aside and concentrate on what makes people see leaving as a better option than staying.
We scanned hundreds of scientific publications and, after applying specific criteria, ended up with 49 articles to include in a systematic literature review. All were based on surveys of the general population (as opposed to health workers or university students, for instance) and used multivariate regression analyses to identify determinants of migration aspirations. In many cases, a single article contained analyses of several populations—of different countries , for instance—and we could therefore base our review of a total of 72 analyses.
We examined 966 statistical results and separated them into 32 distinct determinants. Some, like age, were frequent and straight-forward. Others, like willingness to take risks, were used less often and measured in diverse ways.¹
But with ten or twenty or thirty analyses of a single determinant, pointing in different directions, how is it possible to summarize? Take marital status, for instance. We have 30 analyses that compare people who are single with those who are married (or cohabiting) to see whether being married raises or lowers the likelihood of wanting to migrate. Some analyses draw on surveys with more than 100,000 respondents across several continents, while others cover fewer than 1000 people in a single country. All the analyses provide insights, but in different ways. And even if most results point in the same direction, exceptions can shed light on how marriage affects migration aspirations in specific contexts.
We developed a new form of data visualization to be able to show overall trends without missing out on variation and exceptions. Here’s what it looks like for marital status.
Each analysis is represented by a bubble. The bubbles are coloured and sized according to the region and sample size of the survey, and grouped in three frames according to the results. All the analyses in the ‘negative effect’ frame found that being married or cohabiting lowers the likelihood of wishing to migrate.
In ten studies, the effect of being married wasn’t large enough to be statistically significant. And a single analysis — number 2 — concluded that people who are married are more likely to want to migrate. This was a study from Kyrgyzstan, where newly married couples without children are often considered better prepared to overcome challenges than individual migrants. The study is a reminder that, migration and marriage both vary greatly in meaning and organization across contexts, and that it would be surprising to find a universally consistent relationship between the two. Still, the bubble chart leaves an undeniable overall impression: marriage tends to dampen desires for migration.
Being married, then, is an example of a factor that tends to affect migration aspirations in the same way, even if there are exceptions and inconclusive results. A more bewildering determinant is income. Many studies show that migration aspirations decline with higher incomes (that is, a negative effect), but several other studies conclude that migration aspirations rise with income. And the greatest number of studies fail to find a clear relationship. The bubble chart lays out the divergence:
But again, looking closer helps make sense of the results. Income does not affect migration aspirations in the same way everywhere, and this is reflected in the chart. For instance, study 41 — to the far right in the chart — covers Sub-Saharan Africa, where poverty is widespread and the people with the lowest incomes might lack the capacity to aspire to international migration. So, in this context, people who have higher incomes are more likely to consider living and working in another country.
By contrast, study 26 — a blue bubble to the left in the chart — covers South Korea, a high-income country where people with higher incomes are less interested in moving abroad.
Even if regional differences provide some explanation, the overall relationship between income and migration aspirations can best be described as complicated.¹ But our mission was not to go in depth on specific determinants. Instead, we set out to provide a birds-eye overview of all determinants of migration aspirations. To do so, we had to develop a way of mapping them out.
The most important difference between determinants is how steadily they affect migration aspirations. Marriage, as we just saw, tends to lower migration aspirations, though some studies differ. Other determinants show a clearer pattern of always affecting migration aspirations in the same way, without exceptions. For instance, every single study that considered violence or insecurity found that these ills amplify the desire to leave.
By studying the results for each determinant, we were able to classify them as consistently, overwhelmingly, mainly, or slightly raising migration aspirations. Beyond the slight effects were the divergent ones, like income, that point in different directions. This classification gave us the first dimension of mapping out determinants: the consistency of their effect on migration aspirations.
The second thing that varied tremendously was how often each determinant was included in the analyses. For instance, all but one included age, while only two used information about health. Whatever these two analyses find about the link between health and migration desires, the results are uncertain. This variation gives us the second dimension: certainty. The certainty of each effect depends on the number of articles and analyses that underpin it.
With the two dimensions in place, we can lay out all the determinants. Each one is formulated as a factor that strengthens the wish to migrate. The higher up in the chart, the more consistent is the effect on migration aspirations. The further to the right, the more certain we can be that this relationship holds true across contexts. This is the graph that sums up what we know.
In the top-right we find factors that are both consistent and certain. Being young and knowing current or former migrants are determinants that almost always raise migration aspirations, and which demonstrate this effect across a large number of articles and analyses.
In the top-left corner is a cluster of nine determinants that seem to be highly consistent drivers of migration aspirations, but which are poorly documented. They include corruption and dissatisfaction with public services, such as education and health care. In the top-left corner we also find the two most specifically psychological determinants: being willingness to take risks, and being unhappy in life. Perhaps psychological differences between individuals could add substantially explanations that are based on more conventional demographic or socioeconomic factors.
The colour-coding of the bubbles in the graph allows for reflecting on determinants of different kinds.
Migration-related factors — such as having previous migration experience, or receiving remittances — consistently raise migration aspirations. This reflects the self-sustaining dynamics of migration flows.
Country and community-level development are important for migration aspirations. General poverty, corruption, and insecurity, for instance, make people more inclined to leave. However, each of these factors is covered in few studies, making it hard to determine which aspects of local or national development matter the most.
Individual socio-economic factors — such as being poor, unemployed, or living in a large household — have relatively weak and ambiguous effects on migration aspirations.
Migration research has shown that, also in the world’s poorest countries, there are people who see migration as an opportunity for adventure and personal growth. But our review shows that migration desires tend to be fuelled by frustrations. In general, worse-off individuals in worse-off societies are more likely to aspire to migrate.³
Many questions remain unanswered about what makes people want to migrate. But summing up what is known makes us wiser. While each person has their own specific reasons for desiring to stay or to leave, we can sketch a faint picture of the forces that add up to millions of desires.
Read the full paper: Aslany, Maryam; Carling, Jørgen; Mjelva, Mathilde Bålsrud; and Sommerfelt, Tone (2021) Systematic review of determinants of migration aspirations, QuantMig deliverable 2.2. Southampton: University of Southampton.
This post was originally published on Medium, 3 February 2021.
¹ There are many constraints on the comparability of the effects across the analyses, which we address in detail in the paper. We present results with corresponding caution, but strive to provide the best possible general picture. Comparison of effect sizes was only possibly in a handful of cases, which are not discussed here.
² The relationship is likely to be non-linear, meaning that an increase in income could affect migration aspirations in very different ways at different income levels. Moreover, the interpretation of the income effect depends on whether and how other socio-economic factors are controlled for in the analyses.
³ Many determinants, like marital status and age, can’t be aligned to a good — bad dimension. But most of the determinants that can, support this general statement. The clearest exception is education: Highly educated individuals are more likely to have a wish to migrate than people who are otherwise similar, but have fewer years of schooling.
The research presented here was carried out as part of the project Quantifying Migration Scenarios for Better Policy (QuantMig), which has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement №870299.