The price of mobility: Assessing the impact of Bogotá’s Integrated System of Transportation (SITP) tariff policies on the well-being of vulnerable populations

Last registered on January 03, 2023


Trial Information

General Information

The price of mobility: Assessing the impact of Bogotá’s Integrated System of Transportation (SITP) tariff policies on the well-being of vulnerable populations
Initial registration date
December 14, 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
January 03, 2023, 4:07 PM EST

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


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Primary Investigator

World Bank

Other Primary Investigator(s)

PI Affiliation
World Bank

Additional Trial Information

On going
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
In low- and middle-income countries (LMICs), the most marginalized people often live furthest from the city center and face expensive commutes to access economic opportunities and services. Transit incentives may improve the well-being of of vulnerable populations who otherwise would forgo welfare enhancing trips like healthcare visits and job search opportunities. This study takes advantage of a significant upcoming reform in the transit subsidy policy of Bogotá, which will considerably modify its eligible population, to assess the effects of targeted transit incentives, under imperfect take-up, on mobility, access to healthcare services and job opportunities, as well as effects on overall indicators of well-being such as income, food security and psychological well-being.
External Link(s)

Registration Citation

Bedoya, Guadalupe and Sveta Milusheva. 2023. "The price of mobility: Assessing the impact of Bogotá’s Integrated System of Transportation (SITP) tariff policies on the well-being of vulnerable populations." AEA RCT Registry. January 03.
Experimental Details


In 2014, the Secretary of Mobility of Bogota implemented one of the first city-wide policies to target transport subsidies based on socioeconomic status. The existing national System of Identification of Potential Beneficiaries of Social Programs (SISBEN), a system used to categorize beneficiaries for social programs in Colombia, is used to offer citizens with a score below a cutoff point access to a transport subsidy. Due to a change in the SISBEN, there will be a change in the policy defining eligibility of the subsidy for people using the Integrated System of Transportation (SITP) in the city early 2023. This policy covers millions of people in Bogota, the capital and largest city in Colombia with a population in the metropolitan area of around 11 million people (22% of the country’s population).

We will leverage this policy change and will combine it with an information and encouragement design due to historically low take-up, particularly when changes to the policy have taken place, to provide information on the subsidy and application process to eligible individuals and measure the impact of these incentives on mobility and other economic well-being indicators.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Mobility, including (forgone) trips for accessing health services and job opportunities; physical health and psychological well-being; and other economic well-being indicators such as market work participation, food security, and income.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Probability of registering for the subsidy
Time use for productive, human capital formation and leisure activities
Health trips by type of health service
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We will implement a random control trial on a sample of individuals that are eligible but have not yet accessed the subsidy according to the new policy. The sample will be randomized in two treatment arms and a control group. The first treatment arm will be an information campaign whereby those randomly selected into this group will receive a Whatsapp or SMS message letting them know that (1) this new government policy has come into effect; (2) based on their SISBEN score they are eligible to receive this subsidy; and (3) the address of the closest registration point, how to get there and what is needed for them to register. The second treatment will be an information campaign that includes the same three components, but also includes a fourth component that aims to make more salient the benefit of this subsidy for other beneficial trips such as health or employment trips and highlight the possibility of using the subsidy to take cheaper trips to access healthcare or to seek out job-related opportunities, with potentially information on health facilities or job opportunities accessible through the transport system.
Experimental Design Details
Not available
Randomization Method
Randomization done in office by a computer using a sub sample of the 4000 households interviewed in the baseline. We will include all the individuals who are eligible to the subsidy but are not enrolled in the first 4 months of the policy implementation.
Randomization Unit
Randomization will be at the household level but only one member in the household will be receive the information at a time.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
4000 households
Sample size: planned number of observations
We will use the sample of 4800 individuals in 4000 households that will become eligible and were not eligible before. Based on the experience with the initial implementation of subsidies in 2014, take-up in the first year was only 22%. Therefore, we will start with our sample of 4800 and we will expect up to that number, depending on take-up during the first months.
Sample size (or number of clusters) by treatment arms
We are planning on splitting the sample into 3 equal-sized group ranging between 1,000 and 1,3000 households (depending on the take-up during the first months). One group will receive the information intervention, one group will receive the information treatment plus trip/benefit saliency treatment and the final group will be the control group.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
We conduct power calculations for some of the main outcomes we will estimate. A first order outcome is whether the information intervention increases registration for and usage of the subsidy. The second level focuses on whether usage increased for those that are currently foregoing a larger number of socially beneficial trips such as for healthcare, and if there is a decrease in the number of healthcare trips foregone as well as an increase in healthcare trips taken. We estimate a sample size of 1000 for treatment and 1000 for control, assume a power of 80% and initially we take alpha to be .05 in order to get the minimal detectable effect size. The mean and standard deviation values of the health outcomes are calculated using our sample of 161 individuals from the pilot study we conducted in December 2021. The mean and standard deviation for registration are calculated based on the proportion of the population that had registered for the initial income subsidy established in 2014 one year after it had been established. We find that on average for all three outcomes we can detect an effect size of .14 standard deviations and for other outcomes it varies between 0.13 and 0.16 SD (and between 0.15 and 0.21 with multiple hypothesis testing). Focusing on registration for the subsidy, assuming that the average registration without the intervention is 22%, we can detect a minimum effect size of 5.4 percentage points (.13SD) in the treatment.

Institutional Review Boards (IRBs)

IRB Name
Instituto Nacional de Investigación e Innovación Social
IRB Approval Date
IRB Approval Number