Reference Letters: Experimental Evidence from the Dominican Republic

Last registered on November 18, 2022


Trial Information

General Information

Reference Letters: Experimental Evidence from the Dominican Republic
Initial registration date
November 18, 2022

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
November 18, 2022, 12:30 PM EST

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



Primary Investigator

World Bank

Other Primary Investigator(s)

PI Affiliation
PI Affiliation
Columbia U

Additional Trial Information

On going
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Skills signaling seems to remain one of the most important factors in order to breach the gap between prospective workers and employers. At the same time, expecting an evaluation can change the performance of employees at the workplace. In a setup with more than 2000 unemployed youngsters at risk, going through a vocational training in the Dominican Republic, we test how giving a random subset of them a notice that they will receive a recommendation letter at the end of their internship affects their effort and motivation at the workplace. We also analyze long term results (1 year after vocational training) in employment and other labor-related outcomes, and how having the reference letter from a previous employer can affect labor search prospectives in high informality environments.
External Link(s)

Registration Citation

Bassi, Vittorio, Xavier Gine and Tommaso Porzio. 2022. "Reference Letters: Experimental Evidence from the Dominican Republic." AEA RCT Registry. November 18.
Experimental Details


We evaluate the impact of reference letters in the context of an intervention that promotes job opportunities for children of the beneficiaries of Progresando con Solidaridad (PROSOLI), the national conditional cash transfer program.

The intervention called Youth Employment Training, started in 2012 and is modeled after the Ministry of Labor’s Youth and Employment (Juventud y Empleo) program, which is no longer active. Target participants are 20- to 29-year-old unemployed youth from low-income households in 4 provinces of the Dominican Republic. They are provided technical (driver, assistant, bank teller, etc) and socio-emotional skills in a 40-day course and then offered a two-month non-paid internship at a local firm.

Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Subjective evaluation from supervisors, direct evaluations by enumerators of the youth at work, whether the youth is hired at the firm that offered the internship and self-reported measures by the youth regarding effort level during the internship, probability to find a job, employment status and salary after internship.
Primary Outcomes (explanation)
We use two main sources of data. Survey data collected at baseline and endline and data from supervisor evaluations collected during a visit to the firm where the youth were being trained as part of their internship.
The supervisor evaluation will be constructed as a standardized index using the following items: punctuality, dress code and physical aspect at work, teamwork, efficacy, manners and effort. Each item is evaluated in a 5-point scale ranging from Very bad to Very good.
Self-reported effort level is a 5-point scale from very low to very high effort from the youth survey during the firm visit.
Effort during the internship and other outcomes after the internship such as employment status, salary, etc. come from the endline survey.

Secondary Outcomes

Secondary Outcomes (end points)
Training hours from supervisor to intern, Index of firm knowledge
Secondary Outcomes (explanation)
Training hours is the total of hours the supervisor devoted to train that intern. The index of firm knowledge is an average of the number of correct answers to 4 general questions about the firm.

Experimental Design

Experimental Design
The design includes three experimental arms:
- Control group. Interns randomly assigned to this group will not be informed about a reference letter nor will be given one at the end of the internship.
- Letter "before" group. Interns randomly assigned to this group are told about the letter evaluating their performance (via a call from the program and/or their supervisor) at the beginning of the internship. They are told they will receive the letter at the end of their internship from their supervisor.
- Letter "after" group. Interns randomly assigned to this group are told about the letter evaluating their performance after the internship has concluded when they receive it from their supervisor.
Experimental Design Details
Randomization Method
Randomization done in office by a computer (Stata).
Randomization Unit
The sample is randomized at the course (class) level. Each class has roughly 20 students on average.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
700 students in each of the 3 treatment arms (control, letter before internship, letter after internship)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
MDE for student employed after internship: Baseline mean 0.3, SE 0.46, MDE 0.08 MDE for superv or enumerator evaluation: Control standardized mean -0.8, SE 0.71, MDE 0.12 MDE for self reported effort level: Control standardized mean -0.05, SE 0.89, MDE: 0.16 MDE for salary: Control thousand pesos mean 18.2, SE 9.1, MDE: 1.6 thousand pesos

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number


Post Trial Information

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

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Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials