Randomization for Causality, Ethnography for Mechanisms: Illiquid Savings for Liquor in an Autarkic Society

Last registered on December 06, 2021


Trial Information

General Information

Randomization for Causality, Ethnography for Mechanisms: Illiquid Savings for Liquor in an Autarkic Society
Initial registration date
December 06, 2021

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
December 06, 2021, 2:28 PM EST

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


Primary Investigator


Other Primary Investigator(s)

PI Affiliation
Northwestern University
PI Affiliation
Brandeis University

Additional Trial Information

Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
What should researchers do when confronted with surprising results? Financial access innovations usually leave “temptation” spending unaffected or reduced. However, we found that promotion of savings lockboxes in a largely autarkic society increased alcohol consumption and blood pressure, despite no one reporting intentions to save for alcohol. To probe mechanisms that could explain this pattern, we then used ethnographic methods, including direct observations of drinking (“scans”) and debriefing interviews to discuss the earlier trial results. We learn that sponsoring drinks confers prestige, but the stigma attached to drinking by outsiders likely discouraged reporting intentions to save for it.
External Link(s)

Registration Citation

Godoy, Ricardo, Dean Karlan and Jonathan Zinman. 2021. "Randomization for Causality, Ethnography for Mechanisms: Illiquid Savings for Liquor in an Autarkic Society." AEA RCT Registry. December 06. https://doi.org/10.1257/rct.8670-1.0
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
value of financial assets, value of physical assets, agricultural investments, change in income sources, total expenditures, temptations consumption, blood pressure, fight over money
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The research team, including CBIDSI, worked with the governing council of Tsimane’ to select a sample frame of villages. Our best estimate suggested there were about 120 Tsimane' villages with at least eight households at the time of the study.
We ruled out sampling from villages that were too costly to reach, too unsafe, or that contained people from other ethnic groups. This left 61 villages for our sample. Even these villages are far from the nearest market— a median of about 4 hours travel time. They tend to be even farther from the NGO office in the market town of San Borja where savings could be deposited.

All households in a village were eligible for participation in the study. To enhance participation, brief paid advertisements on the missionary radio station promoted the study shortly before the research team would arrive in each study village. The missionary radio station transmits news and announcements three times a day in Tsimane', and can be heard across the study area.
Within each of the 61 villages, CBIDSI and IPA publicly randomly assigned all the households residing in the village at the time of the visit to treatments or to a control group. These random assignments and baseline surveys took place from March through June of 2011. (For more details on the randomization mechanics and baseline survey see Appendix A and Section 1-D.)
All treatment households received a savings lockbox from CBIDSI that is small, portable, wooden, pest-resistant, and has a slit at the top of the box to insert money (Appendix B). N.b. that the lockbox was not linked to any sort of bank account or to any other service.
The main study arms, randomly assigned in roughly equal proportions within each village, are:

Treatment 1 (T1: Lockbox with Key). Savings box with a key so recipients could open the savings box at any time.

Treatment 2 (T2: Lockbox without Key). This treatment was the same as Treatment 1, except T2 households did not receive a key. Instead the key was kept in the CBIDSI office in San Borja, which, as noted, was several hours of travel time away from most villages in our sample. Our intent was to provide a strong commitment device to facilitate saving for a lumpy expenditure.

Control Group. The remaining households in a village served as a control and received a placebo intervention of six metal plates. The six plates had about the same monetary value as a savings box (~ PPP US$11).
We also randomized which household head received the savings box or plates. Heads received the box or plates after completing the baseline survey, which followed immediately after the random assignment. Due to the high prevalence of two-headed households in the population, and our randomization of which head got the box or plates, we did not attempt to survey most single heads and instead gave them a gift after the public randomization. Our analysis sample thus contains only households headed by two adults.
Experimental Design Details
Randomization Method
Public randomization
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
61 villages
Sample size: planned number of observations
918 households
Sample size (or number of clusters) by treatment arms
320 households control, 292 households treatment with key, 306 households treatment without key
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
Yale University
IRB Approval Date
Details not available
IRB Approval Number
IRB Name
Northwestern University
IRB Approval Date
Details not available
IRB Approval Number
IRB Name
Innovations for Poverty Action
IRB Approval Date
Details not available
IRB Approval Number


Post Trial Information

Study Withdrawal

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Is the intervention completed?
Intervention Completion Date
March 01, 2012, 12:00 +00:00
Data Collection Complete
Data Collection Completion Date
Final Sample Size: Number of Clusters (Unit of Randomization)
Was attrition correlated with treatment status?
Final Sample Size: Total Number of Observations
Final Sample Size (or Number of Clusters) by Treatment Arms
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials