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Job referrals and strategic network formation -- Experimental evidence from urban neighbourhoods in Ethiopia
Last registered on March 03, 2021


Trial Information
General Information
Job referrals and strategic network formation -- Experimental evidence from urban neighbourhoods in Ethiopia
Initial registration date
August 11, 2017
Last updated
March 03, 2021 7:33 AM EST
Primary Investigator
IZA - Institute of Labor Economics
Other Primary Investigator(s)
Additional Trial Information
Start date
End date
Secondary IDs
This experiment tests what influences the linking decisions between individuals through job referrals, and whether these social job networks are formed strategically. I randomly generate job opportunities for young job seekers from dense urban neighbourhoods in Addis Ababa, Ethiopia. Some participants are enabled to refer individuals from their neighbourhood to the same job, and I repeat this experiment for several rounds. Explanatory variables of interest are various referral treatment indicators, various measures of participants' network centrality, as well as dyadic characteristics of two individuals in the social networks. Outcomes of interest are a variety of characteristics of the referred worker, of referral indicators between two individuals, as well as on-the-job performance of the referred worker.
External Link(s)
Registration Citation
Witte, Marc. 2021. "Job referrals and strategic network formation -- Experimental evidence from urban neighbourhoods in Ethiopia." AEA RCT Registry. March 03. https://doi.org/10.1257/rct.2334-5.0.
Former Citation
Witte, Marc. 2021. "Job referrals and strategic network formation -- Experimental evidence from urban neighbourhoods in Ethiopia." AEA RCT Registry. March 03. http://www.socialscienceregistry.org/trials/2334/history/86618.
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Experimental Details
The study is a field experiment on job referrals in day labor markets.

The study comprises three different referral interventions:
1. Referral treatment (open, control) (C)
2. Referral treatment (performance incentivised) (T1)
3. Referral treatment (partly anonymous) (T2)
4. Referral treatment (fully anonymous) (T3)

In detail, the treatments/interventions are defined as follows: The control referral treatment (C) is an un-incentivized, open job referral, similar to `standard' job referrals mostly observed in reality. Workers in this group can invite someone from their neighborhood network to the next work session without incentives and `in the field'. Treatment variation 1 (T1) introduces an incentive treatment, meaning that the worker making a job referral gets a financial reward which is linear in the performance of the invited worker.The second margin of variation shocks the visibility of the referral. Workers in the control referral condition can additionally make partly anonymous or fully anonymous referrals to other workers. Under partly anonymous referrals (T2), the invited worker does not know the identity of the inviting worker, but can reciprocate the referral, while under fully anonymous referrals (T3), reciprocation is now allowed.

In general, the day work I am providing is similar to office-style, workplace-related jobs. The task performance is incentivised for all participants, with a maximum payment of 200 ETB (~ 7 GBP). Work sessions take place on consecutive days or are spread over a whole day. The multiple rounds of the experiment are unannounced ex ante (to ensure comparability between other/same referrals).
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
I measure the effects of the referral type on three main outcomes of interest: i) worker i’s productivity, expressed as correctly entered work teams, P_i, ii) worker i’s network centrality, measured as the number of (in or out) links at baseline, and iii) reciprocity: an indicator that equals one if worker j refers i to the job in period t-1, and i refers j in return in period t .
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Short summary:
- Baseline survey of over 700 individuals;
- Several rounds of a work experiments with three different referral treatments;
- (Short and long run) Follow-up phone survey of participants

- I randomly select 16 densely populated urban neighbourhoods in Addis Ababa, where I collect baseline data on young unemployed individuals and their social networks.
- Within the selected neighbourhoods, I take a census (door-to-door solicitation) of all eligible resident individuals, where eligibility is defined as follows: Permanently living in the selected neighbourhood; between 18 and years of age; not in permanent employment or education.
- These eligible individuals are surveyed with a baseline questionnaire, including questions on personal characteristics, labour market outcomes, behavioural questions, and a detailed social network section, containing a range of questions about every other eligible individual in the neighbourhood.
- I then conduct a work experiment in various locations in Addis Ababa: After the baseline survey, a random subsample from each neighbourhood is invited to a paid day job (the experiment). Sessions take place separate by neighbourhood
- The sessions consist of a work-related and quantifiable effort task. After the completion of the task, participants are randomly allocated to different work referral treatments (described above). The work experiment is repeated over three rounds.
- A few days after participating in work experiment, participants are called by phone and asked follow-up questions on the referral decisions they made.
- Eventually, this experiment tests what influences the linking decisions between participants through the different referral treatments, and whether these social job networks are formed strategically. A particular focus will be on the role of networks centrality in referring other workers. A further focus will be on reciprocity in referring (measured over the multiple rounds of the experiment) as well as permanent exclusion from the temporary day labour market opportunities I am generating.
Experimental Design Details
Randomization Method
Randomisation before sessions done in office by a computer (allocation to work sessions and treatment groups)
Randomization Unit
Individuals (young job-seekers)
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
16 neighborhoods, without clustering. All treatments are implemented in all neighborhoods
Sample size: planned number of observations
Approximately 700 individuals
Sample size (or number of clusters) by treatment arms
150 referral treatment 1, 150 referral treatment 2, 150 referral treatment 3, 150 control group
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB Name
Department’s Research Ethics Committee (DREC), Department of Economics, University of Oxford
IRB Approval Date
IRB Approval Number
Post Trial Information
Study Withdrawal
Is the intervention completed?
Intervention Completion Date
February 28, 2017, 12:00 AM +00:00
Is data collection complete?
Data Collection Completion Date
August 31, 2018, 12:00 AM +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
739 individuals from 16 neighborhoods
Was attrition correlated with treatment status?
Final Sample Size: Total Number of Observations
739 individuals from 16 neighborhoods
Final Sample Size (or Number of Clusters) by Treatment Arms
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)