Impact of a Randomized Controlled Trial in Arsenic Risk Communication on Household Water-Source Choices in Bangladesh

Last registered on February 23, 2016

Pre-Trial

Trial Information

General Information

Title
Impact of a Randomized Controlled Trial in Arsenic Risk Communication on Household Water-Source Choices in Bangladesh
RCT ID
AEARCTR-0001052
Initial registration date
February 23, 2016

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 23, 2016, 3:43 AM EST

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

Locations

Region

Primary Investigator

Affiliation
Universitat Pompeu Fabra and Barcelona GSE

Other Primary Investigator(s)

PI Affiliation
Columbia University
PI Affiliation
University of Dhaka, Bangladesh
PI Affiliation
International Water Management Institute (IWMI), Sri Lanka
PI Affiliation
Duke University
PI Affiliation
Duke University

Additional Trial Information

Status
Completed
Start date
2008-02-01
End date
2008-11-30
Secondary IDs
Abstract
We conducted a randomized controlled trial in rural Bangladesh to examine how household drinking-water choices were affected by two different messages about risk from naturally occurring groundwater arsenic. Households in both randomized treatment arms were informed about the arsenic level in their well and whether that level was above or below the Bangladesh standard for arsenic. Households in one group of villages were encouraged to seek water from wells below the national standard. Households in the second group of villages received additional information explaining that lower-arsenic well water is always safer and these households were encouraged to seek water from wells with lower levels of arsenic, irrespective of the national standard. A simple model of household drinking-water choice indicates that the effect of the emphasis message is theoretically ambiguous. Empirically, we find that the richer message had a negative, but insignificant, effect on well-switching rates, but the estimates are sufficiently precise that we can rule out large positive effects. The main policy implication of this finding is that a one-time oral message conveying richer information on arsenic risks, while inexpensive and easily scalable, is unlikely to be successful in reducing exposure relative to the status-quo policy.

Registration Citation

Citation
, et al. 2016. "Impact of a Randomized Controlled Trial in Arsenic Risk Communication on Household Water-Source Choices in Bangladesh." AEA RCT Registry. February 23. https://doi.org/10.1257/rct.1052
Former Citation
, et al. 2016. "Impact of a Randomized Controlled Trial in Arsenic Risk Communication on Household Water-Source Choices in Bangladesh." AEA RCT Registry. February 23. https://www.socialscienceregistry.org/trials/1052/history/6974
Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)
Samples households are given two types of oral communication regarding the arsenic contamination of the tube-well from which they collect drinking water. The first one is the comparison “status quo” communication and simply states that wells marked green are safe and below the government safety level of 50 ppb and those marked red are above the 50 ppb and unsafe. The treatment group known as the “emphasis” communication states that at any level of arsenic contamination, it is safer to switch to a source that has a lower level of arsenic.

Baseline survey was conducted with the female head of household. Follow-up surveys tracked whether the household switched drinking water source, physically visited the new source if a switch was made, and noted the level of arsenic in the new source.
Intervention Start Date
2008-02-01
Intervention End Date
2008-04-01

Primary Outcomes

Primary Outcomes (end points)
Switching of wells to new drinking water source.
Primary Outcomes (explanation)
Respondents were asked if they had switched their prior well and if the answer was yes, enumerator walked with respondent to the new source and test the arsenic level.

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
In 2003, a local Bangladeshi organization BAMWSP tested tube-wells across Araihazar and labelled green those wells that had an arsenic level below 50 ppb and red those were above 50 ppb. By virtue of an earlier study done in 2005 by the Columbia University Superfund Basic Research Team, many wells were retested. In 2008, wells in 43 sample villages in Araihazar, which were tested in 2005, were labelled with an anodized aluminum plate showing a hand holding a drinking cup that is covered by a large cross when the arsenic level is above 50 micrograms per liter. It also indicates the year when the water sample was collected and the specific arsenic concentration detected in the water tested from that well.

Villages were randomly assigned to receive one of two information treatments. The first one is the comparison “status quo” communication and simply states that wells marked green are safe and below the government safety level of 50 ppb and those marked red are above the 50 ppb and unsafe. The treatment group known as the “emphasis” communication states that at any level of arsenic contamination, it is safer to switch to a source that has a lower level of arsenic. Thus even if the level is 40 ppb, it is safer to switch to one that is, for example, 10 ppb. Likewise if the only viable options are above the 50 ppb level, it is nonetheless better to switch from a 200 ppb to a 100 ppb. The communication is delivered only once for both groups.

Baseline survey was conducted with the female head of household. Follow-up surveys tracked whether the household switched drinking water source, physically visited the new source if a switch was made, and noted the level of arsenic in the new source.
Experimental Design Details
Randomization Method
Pseudo-random number generator.
Randomization Unit
Villages.

Villages were assigned to treatment or control by random sampling stratified by ‘union’ - the smallest geographical unit in Bangladesh.
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
43 vilages
Sample size: planned number of observations
596 households
Sample size (or number of clusters) by treatment arms
23 Treatment villages, 20 Control
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Assuming there are eight households using unsafe wells in each of 42 villages and a 30% switching rate with the standard binary-only message. A 15 percentage point increase in switching due to the emphasis message could then be detected with probability 0.62 if the intra-village correlation is 0.10, and 0.72 with correlation equal to 0.05.
IRB

Institutional Review Boards (IRBs)

IRB Name
Duke University
IRB Approval Date
2008-02-26
IRB Approval Number
2184

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
Yes
Intervention Completion Date
April 01, 2008, 12:00 +00:00
Data Collection Complete
Yes
Data Collection Completion Date
November 30, 2008, 12:00 +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
43 villages
Was attrition correlated with treatment status?
No
Final Sample Size: Total Number of Observations
533 households
Final Sample Size (or Number of Clusters) by Treatment Arms
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials