Estimating the Knowledge and Health Impact of Viamo’s 3-2-1 Service

Last registered on August 18, 2023


Trial Information

General Information

Estimating the Knowledge and Health Impact of Viamo’s 3-2-1 Service
Initial registration date
June 03, 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
June 06, 2022, 5:54 AM EDT

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

Last updated
August 18, 2023, 2:15 AM EDT

Last updated is the most recent time when changes to the trial's registration were published.



Primary Investigator

Swiss Tropical and Public Health Institute

Other Primary Investigator(s)

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Throughout the developing world, people lack access to timely and accurate information in a language they understand. Lack of access to reliable information can result in a waste of resources as well as a range of suboptimal health decisions, including decisions to not seek prenatal care or to use ineffective family planning methods.

To address these knowledge barriers, new call-in services have been developed in LMICS in recent years. These services are free and easily accessible from any phone, and offer validated and generally government approved information to the general population in LMICs. One of the main organizations offering such services is Viamo, a global social enterprise aiming to improve the lives of the poor through mobile services.

The goal of this project is to rigorously assess the impact of the Viamo’s 3-2-1 Service on health knowledge, health behavior and selected health outcomes in Uganda. A total of 6000 women of reproductive age will be enrolled in a randomized controlled trial. Half of these women will be randomly selected for a personal introduction to Viamo’s 3-2-1 service and encouraged to use this service for a year. After one year, health knowledge, health behavior and health outcomes will be compared across treatment and control groups. The primary study outcome will be reproductive health knowledge. Secondary outcomes include use of modern contraception, nutritional status and self-reported health.
External Link(s)

Registration Citation

Fink, Günther. 2023. "Estimating the Knowledge and Health Impact of Viamo’s 3-2-1 Service." AEA RCT Registry. August 18.
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Experimental Details


The main intervention is to encourage randomly selected women to use the 3-2-1 service. Selected women will be invited to use the service after completion of the baseline survey, and then incentivized to use the service through text messages, voice calls and other online materials.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Sexual and reproductive health knowledge
Primary Outcomes (explanation)
The primary study outcome will be a sexual and reproductive health (SRH) knowledge score. This score will be based on a 20 item question knowledge quiz which will be administered at baseline and endline. The score (range 0-20) will be normalized into a z-score for analysis.

Secondary Outcomes

Secondary Outcomes (end points)
Secondary study outcomes include self-reported use of modern contraceptives, self-reported compliance with iron supplementation in pregnancy, haemoglobin levels, blood pressure, body mass index (BMI), blood pressure and birth spacing.
Secondary Outcomes (explanation)
Secondary outcomes cover health behaviors and health outcomes that would ideally be influenced by changes in knowledge. These include intake of supplements during pregnancy, use of modern contraceptives, and birth spacing as key health behaviors, and haemoglobin, BMI and blood pressure as objectively measured health outcomes.

Experimental Design

Experimental Design
This is standard 2-arm trial with individual-level randomization: 50% treatment, 50% control.
Experimental Design Details
Not available
Randomization Method
Randomization will be done on-the-fly via a random number generated by the tablets used by surveyors (at the end of the interview).
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
Sample size: planned number of observations
6000 women ages 18-49
Sample size (or number of clusters) by treatment arms
6000 women ages 18-49 across 200 enumeration areas.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Our study is designed to detect an intention-to-treat effect of 0.1 SDs between treatment and control groups, which corresponds to a treatment effect of 0.2SD on the treated (ATT), assuming a follow-up rate of 90% over the study period.

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number