Incentives for Safety: A Field Experiment in the Ugandan Transit Industry

Last registered on February 07, 2023


Trial Information

General Information

Incentives for Safety: A Field Experiment in the Ugandan Transit Industry
Initial registration date
February 06, 2023

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
February 07, 2023, 11:35 AM EST

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



Primary Investigator

University of Zurich Econ Dep

Other Primary Investigator(s)

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial is based on or builds upon one or more prior RCTs.
The global road safety epidemic, with 1.35 million fatalities annually and 90\% occurring in developing countries, has become a critical issue for economic development. This study investigates the effectiveness of contracts in reducing speeding behavior among motor taxi drivers in urban Uganda. Given the informal and semiformal clustering of workers in this setting, the research design varies the type and visibility to peers belonging to the same cluster of monetary incentives offered to drivers and assesses their impact on driving behavior, labor market outcomes, contract demand, and the environment. The use of GPS technology enables the collection of high-frequency driving behavior data, which serves as the basis for designing credible contracts and observing behavior during and after the contract period.
External Link(s)

Registration Citation

Raisaro, Claude. 2023. "Incentives for Safety: A Field Experiment in the Ugandan Transit Industry." AEA RCT Registry. February 07.
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Driving behavior:
- Dummy variable indicating whether a speeding violation (driving above 50 kph) has been committed in a given day
- Average excess speed in a given day

Labor market outcomes:
- earnings
- labor supply
- productivity
Primary Outcomes (explanation)
Driving behaviors and labor market outcomes are respondent-by-day measures. The frequency reflects the unit of observation (respondent by day).

Secondary Outcomes

Secondary Outcomes (end points)
Demand for commitment:
- Dummy variable indicating whether respondent picks a dominated contract
- Willingness to pay for the contract

Labor market outcomes:
- share of recurrent customers
- number of new contacts from customers

Driving behavior:
- Air pollutant emissions: carbon footprint
- Expected average fine
Secondary Outcomes (explanation)
Demand for commitment of a respondent is elicited at the end of the study period. The commitment device is a financial contract that pays based on speeding behavior (details about the contract in the design section). The demand elicitation follows the same method adopted in AEARCTR-0010635.
Demand for commitment of a respondent is elicited at the end of the study period.
Labor market outcomes and carbon footprint of a respondent are calculated at daily level.

Expected average fine based on fines for speeding declared at baseline by the study sample.

Experimental Design

Experimental Design
360 motor-taxi drivers, all operating from different taxi stations in the metropolitan area of Kampala, Uganda, are randomly assigned to receive an offer to access financial incentives for ten days. Each respondent is asked to answer a phone survey every two days for a time period of two weeks.

Participants were randomly assigned to three treatment groups with the following goals. First, a sub-sample is offered financial incentives to reduce speed excess; to control for income effects, the remaining part of the sample is offered a flat payment regardless of the driving behavior. Second, to study the impact of financial incentives that can be used to counter peer pressure, for a subset of respondents, the financial incentive offer is publicly disclosed to the peers working at the same taxi station.

Data on participants' behavior is collected in two ways: a) a brief phone survey is administered right before, during, and after exposure to treatment; b) a free-of-charge GPS tracker was installed in the motorbikes of all participants approximately two months before the intervention.
Experimental Design Details
The financial incentives are presented in the form of a contract that pay pays UGX 6,000 if speed never exceeds 50 kph and pays UGX 2,000 regardless of the driving behavior, daily for a total of ten days. Speed is measured through a GPS device installed in the motorbike of each study participant. Respondents are exposed to the GPS technology and provided with a mobile app to monitor their own past behavior for about one month before intervention.
The contract is the same as the one offered in the demand experiment AEARCTR-0010635: assignment to treatments is incentive-compatible with the demand experiment.
The treatment is communicated during the first in-person free-of-charge check of the GPS device, a month after its installation, at their own taxi station. All respondents are provided with a short written document about the GPS device and a token of appreciation of UGX 1,000 for each phone call completed. The incentives are explained orally. Phone calls begin before treatment. For the contract to start, the respondent must undergo the GPS check-up visit and answer the first follow-up phone call. The treatment features are reminded by the field officer during each private phone call made right before and during treatment.

1) The Flat Payment Group receives UGX 4,500 per day regardless of the driving behavior. The payment amount corresponds to the realized payment under the private incentives contract in the pilot sample. The incentives are explained privately to the respondent in the proximity to his taxi station.

2) The Private Incentive Group receives the contract outlined above privately: no other driver is informed about the offered contract, nor the willingness to pay for that contract. The incentives are explained privately to the respondent in the proximity of his taxi station.

3) The Public Incentive Group receives the same incentives offered to respondents in Group 2) except for one feature: the offer is made public to the peers working at the same taxi station. The offer corresponds to the "public excuse" offer from experiment AEARCTR-0010635: the financial incentive offer is made public, while the willingness to pay for the incentive remains private.
Incentives are made public in the following way: the field officer explains the offer to the respondent at the taxi station, in front of his peers present at that moment.

A small sub-sample is randomly assigned to the remaining treatment conditions of the demand experiment to preserve incentive compatibility and avoid any deception of the respondents.

Treatment payments are made twice: after 3 days and at the end of the contract. Information about the realized driving behavior is disclosed only to the respondent via an ad-hoc mobile app and a daily text message. The information about whether the speed exceeded 50 kph in a given day is disclosed to the respondent the following morning. No mention of payment is made in the text message or mobile app. The expected payment is discussed with the field officer during the follow-up phone calls.
Payments of the token of appreciation for completing the phone survey are sent the same day. All payments are made via mobile money.

The GPS tracker allows for measuring a set of driving behavior and labor supply outcomes, including speed, route choice, length, moving duration, number of rides, and number of customers. These measures are used jointly with survey answers from the questionnaire administered right before and during treatment. I am interested in the effect of the contracts as a function of the expected payoff from the contract, contract demand, profits, and share of recurrent customers at baseline. I will compare changes in outcome across treatment arms 1) vs 2) and 2) vs 3), controlling for outcome at baseline.
Randomization Method
Randomization done in office by computer
Randomization Unit
Individual (respondent)
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
360 respondents (cluster)
Sample size: planned number of observations
3600 observations (respondent-day)
Sample size (or number of clusters) by treatment arms
550 observations (55 clusters) in arm "Flat payment"
1800 observations (180 clusters) in arm "Private contract"
1250 observations (125 clusters) in arm "Public excuse contract"
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
I collected GPS data for 40 bikes for a period of about 6 months. I used this data to simulate treatment effects and calculate the necessary sample size for each treatment arm. I randomly extracted 360 strikes over 10 consecutive days to construct a simulated panel of 360 drivers receiving the treatment for 10 days. I focus on the speeding violation dummy as an outcome. Within-subject correlation ranges between 0.26 and 0.41 across strikes. At baseline, the mean and standard deviation are (.85,.32) for the speeding indicator. Controlling for outcome values pre-treatment, I can detect a minimum treatment effect of .1 standard deviation with .8 power with the following sample size: 520 obs in control (52 clusters), 1750 obs in the private contract arm (175 clusters), and 1210 obs (121 clusters) in the public excuse contract arm. The private contract arm serves to test both the effect of the private contract compared to flat payment and to test the differential effect of private vs. public incentives.

Institutional Review Boards (IRBs)

IRB Name
MUREC Research Ethics Committee
IRB Approval Date
IRB Approval Number


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