Information and Irregular Migration: Evidence from a Field Experiment in Nigeria

Last registered on December 19, 2021


Trial Information

General Information

Information and Irregular Migration: Evidence from a Field Experiment in Nigeria
Initial registration date
December 17, 2021

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
December 19, 2021, 1:25 PM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.


Primary Investigator

WZB Berlin Social Science Center

Other Primary Investigator(s)

PI Affiliation
RWI - Leibniz Institute for Economic Research
PI Affiliation
WZB Berlin Social Science Center and Columbia University
PI Affiliation
IPA Nigeria
PI Affiliation
University of Michigan

Additional Trial Information

On going
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Policy projections and recent research suggest that large numbers of irregular migrants from sub-Saharan Africa will continue to attempt to make their way to Europe over the next few decades. In response, European countries have made and continue to make significant investments in information campaigns designed to discourage irregular African migration. These campaigns are frequently accompanied by evaluations of some sort but, to our knowledge, none have involved a well-powered, randomized controlled trial with a representative sample and actual migration as an outcome.

This pre-analysis plan describes the design of field experiment that addresses the following core questions: Are beliefs about migration-related risks, interest in attempting irregular migration, and actual migration decisions responsive to information campaigns highlighting the risks of the migration journey? The project takes place in Edo and Delta states, in the South-South region of Nigeria, a major Sub-Saharan African source of irregular migrants to Europe.
External Link(s)

Registration Citation

Beber, Bernd et al. 2021. "Information and Irregular Migration: Evidence from a Field Experiment in Nigeria." AEA RCT Registry. December 19.
Experimental Details


Our study's information interventions are inspired by those that have been funded by European governments, many of which focus on features of the (often harrowing) migration journey. Migration decisions are believed to involve a weighing of risks, and the objective of our treatments is to provide factual, truthful information about the many risks involved in attempting irregular migration along the Mediterranean Route. Our design includes two waves of treatments, described below.

Intervention 1: Comprehensive information treatment

We provide a set of treated households in Nigeria with a realistic summary of the chances of successfully reaching Europe and the risks of irregular migration, with an emphasis on the risk of death, injury, exposure to sexual violence, and enslavement along the migrant trail across the Sahara desert and the Mediterranean Sea. The relevant control group does not receive this information from us. This treatment is delivered in the form of an in-person script and a video message with testimonials from migrant returnees, who attempted the journey but did not reach Europe and were repatriated. The treatment also includes an active processing component designed to ensure subject engagement and to help overcome motivated reasoning.

The informational content builds on qualitative and survey research carried out in Edo state's capital, Benin City, in 2018, which suggested high levels of uncertainty and widespread misinformation about irregular migration-related risks along the Mediterranean route. This prior work suggests that the information provided in intervention 1 is (a) not already widely known and (b) is relevant for migration-related decision-making in our research setting.

This treatment is comprehensive and intense in order to enable us to see whether this kind of information intervention can lead to sustained, long-term, behavioral change. This remains an important open question and one that is particularly relevant for practitioners, as our script mirrors components of existing policy initiatives. However, it means that we will not be able to assess the efficacy of any one particular statement of fact. We partially separate elements of this treatment in our second intervention described below. All of the facts mentioned are accurate to the best of our knowledge at the time the script was written, and we indicate sources as they were provided to subjects upon request.

Intervention 2: Decomposition experiment

We implement a second experiment with a smaller group of subjects beyond the scope of intervention 1, in which we treat individuals with only one set of components of the information treatment. These sets of components are:

(1) Factual information, including a detailed, fact-heavy script focusing on the risks of the migration journey and the likelihood of being granted asylum in Europe, as shown above;

(2) Factual information in combination with a motivated reasoning exercise, designed to overcome a bias toward optimism in how individuals assess risk when they face it personally as opposed to when other comparable individuals do;

(3) Emotionally charged content, delivered by way of a video of interviews with migrant returnees, who attempted the irregular migration journey but did not reach Europe.

Each of these treatments is delivered to individuals by way of a preset video. A fourth subset of individuals functions as control group and does not receive any of these materials.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
(1) *Beliefs*: beliefs about risks associated with irregular migration from Nigeria to Europe along the "Mediterranean Route"
(2) *Motivated reasoning*: the size of the gap between beliefs about irregular migation-related risks to oneself and to others
(3) *Intentions*: self-reported interest in attempting irregular migration from Nigeria to Europe
(4) *Migration behavior*: actual irregular migration attempts made by households included in the study
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
(5) *Uncertainty*: confidence in beliefs about irregular migration-associated risks
(6) *Substitution*: interest in and actual *regular* migration attempts
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We recruit 3,200 households at baseline with consenting heads of household and selected individuals, of which 1,600 are assigned to a comprehensive information treatment (intervention 1) and the remainder to the control group (who receive no information about irregular migration-related risks). For the decomposition experiment (intervention 2), we assign 250 individuals to each of three treatment groups (corresponding to different components of the information treatment in intervention 1), with another 250 assigned to the control group, for a total of 1,000 subjects for this experiment. Half of these subjects are drawn from the first intervention's control group in the first batch of the baseline, for whom one-year follow-up data has already been collected in the course of the midline survey, and half are drawn from the subject pool available from a pre-baseline survey.
Experimental Design Details
Not available
Randomization Method
Random selection of enumeration areas and buildings was carried out in R, with oversampling of urban areas. We use weights to adjust for this oversampling as needed when we claim representativeness. The random sampling of households and individuals was implemented in SurveyCTO, as were the randomized experimental assignments for the information treatment (intervention 1). Randomization for the decomposition experiment (intervention 2) was again carried out in R.
Randomization Unit
The unit of randomization in our study (both interventions 1 and 2) is the individual.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
Sample size: planned number of observations
Intervention 1: 3,200 individuals. Intervention 2: 1,000 individuals.
Sample size (or number of clusters) by treatment arms
Intervention 1: 1,600 treated individuals (received information about the risks of irregular migration); 1,600 control individuals (no migration-relevant information provided).

Intervention 2: 250 individuals - factual information treatment, 250 individuals - factual information + motivated reasoning exercise treatment, 250 - individuals - emotionally charged content treatment, 250 individuals - control.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
In a basic comparison of group means with significance level 0.05, 80% power, and unit standard deviations, the MDE is .099 of a standard deviation for a sample of 3,200 individuals.

Institutional Review Boards (IRBs)

IRB Name
IPA Institutional Review Board
IRB Approval Date
IRB Approval Number
IPA IRB Protocol #: 15057
IRB Name
WZB Ethics Review Committee
IRB Approval Date
IRB Approval Number
IRB Name
University of Benin, Ad Hoc Social Science Ethics Committee
IRB Approval Date
IRB Approval Number
Analysis Plan

Analysis Plan Documents

Information and Irregular Migration: Pre-Analysis Plan

MD5: f452e0ede3a0199edd5d8583a0edcd9b

SHA1: ec3359d1b2c4fcdb8e23d8961370891de77ed58e

Uploaded At: December 17, 2021