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The impact of a “carry-around” soft commitment device on savings and temptation spending: Evidence from a field experiment in Indian slums
Last registered on September 04, 2019


Trial Information
General Information
The impact of a “carry-around” soft commitment device on savings and temptation spending: Evidence from a field experiment in Indian slums
Initial registration date
December 18, 2018
Last updated
September 04, 2019 8:24 AM EDT
Primary Investigator
University of Goettingen
Other Primary Investigator(s)
PI Affiliation
University of Goettingen
Additional Trial Information
On going
Start date
End date
Secondary IDs
We study the impact of a portable "soft" commitment device on the financial behavior of low-income slum dwellers in urban Pune, India. The portable device may add value to existing commitment designs by activating its binding appeal precisely at the point in time when spending decisions are made. 1650 individuals will be randomly allocated to receive either a zip purse and a lock box (treatment arm) or a lock box only (control arm). Both groups are asked to formulate a savings goal and commit to a step-by-step individualized savings plan. We will estimate the causal impact of receiving the portable device on total savings amounts and temptation spending. Further, we will compare study arms with regards to their borrowing activity, expenditure levels, resilience to economic shocks, financial self-efficacy, and female empowerment. Findings from this study can enhance the current understanding of how commitment devices may help alleviate behavioral biases and temptations.
External Link(s)
Registration Citation
Steinert, Janina, Rucha Vasumati Satish and Sebastian Vollmer. 2019. "The impact of a “carry-around” soft commitment device on savings and temptation spending: Evidence from a field experiment in Indian slums." AEA RCT Registry. September 04. https://doi.org/10.1257/rct.3682-3.0.
Former Citation
Steinert, Janina, Rucha Vasumati Satish and Sebastian Vollmer. 2019. "The impact of a “carry-around” soft commitment device on savings and temptation spending: Evidence from a field experiment in Indian slums." AEA RCT Registry. September 04. http://www.socialscienceregistry.org/trials/3682/history/52821.
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Experimental Details
The proposed intervention, named “Aaj bachat kara, udya khush raha” (Marathi for “Save today, be happy tomorrow”), consists of a portable savings device (zip purse) that is provided in addition to a stationary savings box. It is thereby hypothesized that the carry-around savings device fulfils both a reminder and earmarking function that may invoke feelings of guilt and failure if money is spent on temptation goods.

The stationary device is a lockbox. Keys are distributed to the participant and his/her partner residing in the same housheold. The lock box can thus be opened at any time. Money thus retains its liquidity and can be accessed in urgent cases or emergencies. The intervention can therefore be conceived of as a “soft nudge” rather than a “hard” and fully coercive commitment.

Savings devices are distributed to participants during home visits. In these visits, participants are also encouraged to formulate a savings goal and commit to an individualized savings plan that outlines specific steps on how to reach their savings goal.

(Active) Control:
The control group receives only the stationary and not the portable savings device. Similar to the treatment group, the device is delivered in home visits and participants are asked to formulate both a savings goal and detailed savings plan.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
1. Total Savings
2. Temptation Spending
Primary Outcomes (explanation)
1. Total Savings:
Includes savings held in the lockbox and also savings held elsewhere (e.g., bank account, savings group, post office). Enumerators will be instructed to physically count the money stored in the lockbox.
2. Temptation Spending
We introduce a new measure of temptation spending by capturing past as well as desired future consumption of nine selected food non-food items (e.g., alcohol, tobacco, gambling,...). Temptation goods are said to differ from “essential” goods in that they provide utility when consumed, but not in anticipation of their consumption. Based on this standard definition, we classify each of the selected items only as a ‘temptation good’ if the reported amount for past expenses exceeds the desired future amount. For each respondent, these divergences will then be added up into a total amount of past-month temptation expenditures. This approach allows us to define a unique set of temptation goods for each individual respondent, without reliance on a priori, researcher-defined temptation categories.
We further include a self-rated temptation index based on the following three items:
-In the past month, I spent money on things that I didn’t really need.
-In the past month, I bought something and later regret that I did.
-In the past month, I found it difficult to really control on how I spend my money

Secondary Outcomes
Secondary Outcomes (end points)
1. Self-Efficacy
2. Total Debt
3. Resilience to Economic Shocks Female Empowerment
4. Past-month Household Expenditures
5. Female Empowerment
Secondary Outcomes (explanation)
1. Self-Efficacy
Items for the psychological concept of self-efficacy were drawn from the \emph{Internality, Powerful Others and Chance (IPC)} scale (Levenson, 1981) as well as from financial self-efficacy scales used previously in Steinert et al. (2018) and Lown (2011). Individual items will be aggregated into an index based on PCA.

2. Total Debts
In addition to total savings amounts, we will also capture outstanding debts in the past month.

3.Resilience to Emergenies:
Further to this, our survey will measure respondents’ capacity to cope with potential health or other emergencies. This will be determined based on whether participants have managed to cover the costs for potential medical treatment and medicine in the past month. We will further capture whether respondents have experienced some sort of income shock in the past six months and if so, how difficult it was for them to cope with this shock.

4. Past-month Household Expenditures
To assess the potential downstream impact of saving, we will also consider a more distal indicator of household welfare, namely past-month food and non-food expenditures.

5. Female Empowerment
Previous financial inclusion literature has routinely assessed program impacts on female empowerment. In line with this, we will measure female empowerment (for the female sample only) based on a PCA-weighted index composed of seven individual items.
Experimental Design
Experimental Design
1650 slum dwellers from the city of Pune, India, will be enrolled in the trial. 825 participants will be randomly allocated to the treatment group and 825 participants to the control group. Randomization will be stratified by participant sex, income, and present bias. Eligibility criteria are a) being 18 years and older, b) having some income (employment or other) at least once per week or on a monthly basis, and c) holding at least some decision making power over how money is spent. The study aims for a roughly equal share of female and male participants.
Experimental Design Details
Randomization Method
Randomization to treatment and control group will be done on a 1:1 ratio, implemented in Stata, stratified by participant sex, baseline savings, and present biased time preferences.
Randomization Unit
Individual Randomization
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
825 participants treatment, 825 participants control.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
For desired power of 0.80 with two-tailed p<0.007 (for seven hypothesis tests) and a minimum detectable effect size of 0.37, the target sample size for the trial is 1500 individuals. We oversampled by 10% to account for attrition.
IRB Name
Ethics Committee of the University of Goettingen
IRB Approval Date
IRB Approval Number
EK 10.-35/2018
Analysis Plan
Analysis Plan Documents
Pre-Analysis Plan



Uploaded At: September 02, 2019

Pre-Analysis Plan

MD5: 6b7435cbaed5328949f298a5926d7aca

SHA1: ea3cd915db215640f511c5ea6c39d65d67b4e4a0

Uploaded At: September 04, 2019

Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)