NEW UPDATE: Completed trials may now upload and register supplementary documents (e.g. null results reports, populated pre-analysis plans, or post-trial results reports) in the Post Trial section under Reports, Papers, & Other Materials.
Information and Social Interaction in Savings Decisions in the United States
Initial registration date
January 11, 2017
January 11, 2017 4:52 PM EST
Other Primary Investigator(s)
University of California, Berkeley
Additional Trial Information
This paper analyzes a randomized experiment to shed light on the role of information and social interactions in employees' decisions to enroll in a Tax Deferred Account (TDA) retirement plan within a large university. The experiment encouraged a random sample of employees in a subset of departments to attend a benefts information fair organized by the university, by promising a monetary reward for attendance. The experiment multiplied by more than five the attendance rate of these treated individuals (relative to controls), and tripled that of untreated individuals within departments where some individuals were treated. TDA enrollment five and eleven months after the fair was signifcantly higher in departments where some individuals were treated than in departments where nobody was treated. However, the effect on TDA enrollment is almost as large for individuals in treated departments who did not receive the encouragement as for those who did. We provide three interpretations - differential treatment effects, social network effects, and motivational reward effects - to account for these results.
Duflo, Esther and Emmanuel Saez. 2017. "Information and Social Interaction in Savings Decisions in the United States." AEA RCT Registry. January 11.
Treated department + letter: Employees received the letter promising the monetary reward for attending the fair.
Treated department + no letter: Employees who did not receive the letter, but were in the same department as someone who did. Non-treated department (control): Employees in departments where no one received the letter.
Intervention Start Date
Intervention End Date
Primary Outcomes (end points)
Fair attendance, TDA enrollment (at 4.5 and 11 months), Effects of financial incentive on attendance and enrollment, Effects of social interactions on attendance and enrollment
Primary Outcomes (explanation)
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
This evaluation studies the influence of information and social networks on university employees' decisions to enroll in a voluntary TDA retirement plan. In an effort to increase TDA enrollment, this university set up a benefits fair to disseminate information about different benefits plans offered by the university. Researchers offered a $20 reward for attending the fair to a random group of employees within a subset of randomly selected university departments. The study traced the reward's effects on recipients' fair attendance and TDA enrollment, as well as the social network's effects on fair attendance and TDA enrollment of non-recipients in the same department as reward recipients.
Experimental Design Details
Computer (Stata code)
In the first step, we randomly selected two-thirds of the departments of the university (220 out of a total of 330) as follows. In order to maximize the power of the experiment (in a context in which we know there are strong department effects), we fist matched departments according to their size (i.e., number of employees) and participation rate in the TDA before the fair. We separated departments into deciles of participation rates among the staff. Each decile contains 33 departments. We then ranked them by size within each decile, and formed groups of three departments by putting three consecutive departments on these lists in the same triplet. Within each of these triplets, we randomly selected two departments to be part of the group of treated departments. In the second step, within each of the treated departments, any individual not enrolled as of August 2000, was selected with a probability of one-half to receive the letter treatment.
Was the treatment clustered?
Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
Treated department + letter: 2,039 individuals
Treated department + no-letter: 2,129 individuals
Non-treated department (control): 2,043 individuals
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
INSTITUTIONAL REVIEW BOARDS (IRBs)
Post Trial Information
Is the intervention completed?
Intervention Completion Date
November 30, 2000, 12:00 AM +00:00
Is data collection complete?
Data Collection Completion Date
October 31, 2001, 12:00 AM +00:00
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
Reports, Papers & Other Materials
The Role of Information and Social Interactions in Retirement Plan Decisions: Evidence From a Randomized Experiment
Duflo, Esther, and Emmanuel Saez. 2003. "The Role of Information and Social Interactions in Retirement Plan Decisions: Evidence from a Randomized Experiment." The Quarterly Journal of Economics 118(3): 815-42.
REPORTS & OTHER MATERIALS