Sunday, March 24, 2013

Nudge Database II

This is Part 2 of the Nudge Database.
Part I || Part III || Part IV || Part V || Part VI || Part VII || Part VIII || Part IX ||  Part X || @Makeuya 

Nudge:  The authors ran a trial on Facebook using social proof to induce people to vote during the 2010 U.S. Congressional Elections. Treatment Group 1 contained 60 million people who saw a neutral ‘get out the vote’ ad along with a clickable “I voted” button. Treatment group 2 contained 600,000 people who saw an ad (pictured) embedded with a social proof element showing which of their friends had voted. The Control group contained 600,000 people who received no imploration to vote.

The results showed that users who received the social message were more likely to have clicked “I voted”. While Treatment Group 1 and the Control group had the same turnout rates, Treatment group 2, which implemented the social proof mechanism, had significantly more turnout rates. The researchers estimate that the direct effect of the Facebook social message on users who saw it generated an additional 60,000 votes and the effects of the social network – of social contagion among friends – yielded another 280,000 more, for a total of 340,000. In other words the social network yielded an additional four voters for every one voter that was directly mobilized. To verify whether the participants really did vote rather than just claim they the authors compared turnout rates among their treatment & control groups and found 4% of those who said they voted had not. 

Tags : voting / social proof / facebook 

Source: Bond et al. (2012), 'A 61-million-person experiment in social influence and political mobilization', Nature.
Writeup here, worth reading in detail.

Nudge:  Using financial incentives to encourage prosocial behavior by levying a 5 cent tax on plastic bags in Washington D.C.-  Despite the trivial fee, it had a significant effect on disposable bag use. A similar policy that offered a 5 cent bonus had no significant effect on behavior. In the graph note the before/after effects in Montgomery County of introducing the tax. 

Tags : social norms / plastic bags / financial incentives 

Source: Homonoff (2012) 'Can Small Incentives Have Large Effects? The Impact of Taxes versus Bonuses on Disposable Bag Use', Job Market Paper.

Nudge: Direct mail field experiment in South Africa which randomized advertising content about loans to measure  the effects of different framing on demand. Found several interesting things, e.g. including a photo of a pretty girl increased loan demand by as much as if you had reduced the interest by 25% of the original rate.

Tags : framing / loans / advertising  

Bertrand et al. (2010), ‘What’s Advertising Content Worth? Evidence from a Consumer Credit Marketing Field Experiment’, The Quarterly Journal of Economics.

Nudge: Three field experiments looking at increasing savings with text message reminders.

Goal-specific reminders were considerably more effective than generic ones, resulting in a 16% increase in savings compared to 6% for the generic reminder and 0% for the control which received no reminders.

Tags : inter-temporal choice / present-bias / text messages / savings

Source: Karlan et al. (2010), 'Getting to the Top of Mind: How Reminders Increase Saving', NBER Working Paper.

Nudge: Encouraging Kenyan farmers to match their actions with their intentions regarding their use of fertilizer by mitigating their present-bias & procrastination tendencies through improved behavioral design. Specifically, treatment groups received a visit from an NGO officer offering them vouchers to buy fertilizer in the future and offers to deliver it for free, though this would be prohibitively expensive to do on a large scale. Although the treatment group purchased significantly more fertilizer, read the conclusion for important limitations of the study.  

Tags : present-bias / self-control / time-discounting / fertilizer  

Source: Duflo et al. (2010), ‘Nudging Farmers to Use Fertilizer : Theory and Experimental Evidence from Kenya’, American Economic Review.

Nudge: Two treatments offered ‘ordinary’ and ‘ordinary & commitment’ savings accounts to Malawian farmers. Commitment accounts allowed savers to restrict access to their own money until a designated date. Control group was not offered any account. Only commitment accounts had significant impacts on savings, later allowing those people to purchase 26% more agricultural inputs than the Control. 

Tags : time-discounting / self-control / commitment / savings 

Source: Brune et al. (2011), 'Commitments to Save : A Field Experiment in Rural Malawi', World Bank Policy Research Working Paper.


Nudge:  Examined manipulating the position of food on a restaurant menu. Found items placed at the beginning or end were found to be up to twice as popular as when the same items were placed in the centre of the menu. 

Tags : obesity / position effects 

Source: Dayan & Hillel (2011), 'Nudge to nobesity II: Menu positions influence food orders', Judgment and Decision Making.

Nudge: Automatically enrolled employees into a 401(k) plan, finding that the default was incredibly sticky both in terms of how many people did not opt out of it & how many people stuck with the automatic savings rate. The latter issue, potentially problematic if people did not save enough, was later tackled by ‘Save More Tomorrow’.

Tags : defaults / inertia / savings 

Source: Madrian & Shea (2001), 'The Power of Suggestion: Inertia in 401(k) Participation and Savings Behavior', The Quarterly Journal of Economics.

Nudge:   Targeting child immunization in India with small incentives. 34 villages were randomly divided into 3 groups. A & B were treatment groups, C was the control. 
A-   A monthly immunisation camp; 
B-   A monthly immunisation camp with incentives (raw lentils & metal plates for completed immunisation)
C-   Control (no intervention) 
Incredibly, Group B outperformed A in achieving full immunization by a factor of two.

Tags : immunization / incentives 

Source: Banerjee et al. (2010), ‘Improving immunisation coverage in rural India: clustered randomised controlled evaluation of immunisation campaigns with and without incentives’, British Medical Journal.

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