Do behavioral interventions have durable effects?

That’s the title of of a new paper by Hunt Allcott and Todd Rogers.

From the abstract:

Interventions to affect repeated behaviors, such as smoking, exercise, or workplace effort, can often have large short-run impacts but uncertain or disappointing long-run effects. We study one part of a large program designed to induce energy conservation, in which home energy reports containing personalized feedback, social comparisons, and energy conservation information are being repeatedly mailed to more than five million households across the United States.

We show that treatment group households reduce electricity use within days of receiving each of their initial few reports, but these immediate responses decay rapidly in the months between reports. As more reports are delivered, the average treatment effect grows but the high-frequency pattern of action and backsliding attenuates. When a randomly-selected group of households has reports discontinued after two years, the effects are much more persistent than they had been between the initial reports, implying that households have formed a new “capital stock” of physical capital or consumption habits. We show how assumptions about long-run persistence can be important enough to change program adoption decisions, and we illustrate how program design that accounts for the capital stock formation process can significantly improve cost effectiveness.

What does this mean? Well, I find it best to view as a stylized graph: 

Every time a mailing is made, electricity consumption drops a bit in response to the feedback about usage. While it has a tendency to tick back up over the next few days, the effect remains. Over many months, a new habit of electricity usage is formed. Once the mailers stop, the new, lower level of consumption remains.

This is the first such paper to look at the long-term, durable influence of such interventions, and it is reassuring to see that (at least in this case), the intervention does not only have a short-run influence on behavior, but also a long-term change in how the individual consumes.


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