Credit where it’s due: Reducing credit card debt
Last registered on September 12, 2017


Trial Information
General Information
Credit where it’s due: Reducing credit card debt
Initial registration date
September 11, 2017
Last updated
September 12, 2017 4:13 PM EDT

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Primary Investigator
Harvard University
Other Primary Investigator(s)
Additional Trial Information
In development
Start date
End date
Secondary IDs
The aim of the study is to test the impact of behavioural economics-informed reminders on the credit card repayment behaviour of individuals who have persistently been making low repayments. Providing electronic notifications and proactively contacting consumers who persistently make small repayments were specifically actions proposed for behavioural testing in the Australian Government’s consultation paper titled ‘Credit Cards: Improving Consumer Outcomes and Enhancing Competition’. It is thought that consumers who make small repayments are experiencing financial hardship and/or are unaware of the consequences of under repayment and the options available to pay off debt more quickly.
External Link(s)
Registration Citation
Hiscox, Michael. 2017. "Credit where it’s due: Reducing credit card debt." AEA RCT Registry. September 12.
Experimental Details
Customers will receive an electronic notification reminding them that payment on their credit card bill is due next week
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
Customer repayments on their credit card balance by the due date. include:
Primary outcomes: (1) % of credit card balance paid each month ($ amount paid/closing balance) (2) $ amount paid each month.
Secondary outcomes: (1) $ balance owing each month (2) $ interest and fees each month.
Outcomes will be evaluated at the individual customer level, and sub-group analysis will be performed to examine effects for different demographic groups.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Customers will be randomly allocated to receive a reminder message.
Experimental Design Details
Not available
Randomization Method
Customers who meet the eligibility criteria will be divided into two segments based whether they are eligible to receive a SMS or EDM. Within each channel, customers will be randomly distributed among 6 cells stratified by credit card balance and age group.
Randomization Unit
At the individual customer level.
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
Sample size: planned number of observations
Approximately 25,000 individuals
Sample size (or number of clusters) by treatment arms
Approximately 1,600 individuals in each cell for the email channel, and approximately 2,500 individuals in each cell for the SMS channel.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
For the outcome measure of $ amount paid per month, assuming a two-tailed alpha = 0.05 and power = 0.80, the study is powered to detect a $22.50 difference in the email channel, and an $18 difference in the SMS channel. This is based on repayment data from February 2016 to January 2017. Once repayment data from June 2016 to May 2017 is available, it is possible that the study will be powered to detect slightly different effects.
IRB Name
BETA Ethics Committee
IRB Approval Date
IRB Approval Number
ETH 2017 – 006