Unintended Consequences: bag bans

Potential bias: if bring-your-bag was equivalent to free-throw rate I’d be an all star.

Update: since drafting this post there was a related interview on Data Skeptic with Becca Taylor about this. It was good. 

Our evolutionary advantage was to see cause and effect. This If this then that approach to life kept us alive. It was a simple rule that worked great in a simple system. Modern life is not so simple, but that doesn’t mean we need complicated rules (see Gall’s Systems Bible).

A modern simple rule with great effect is to ask and then what when faced with an intervention. There’s always cascading effects and asking and then what is a way to look for the larger effects.

Chicago, 2016-2017, offered a chance to see this question in terms of plastic bags at the grocery store. In sequential months, there was a ban on thin plastic bags, no ban or tax, and then a tax on disposable bags.

This legislative two-step occurred because the first bag ban was a debacle. Lawmakers gave the wrong answer to the and then what question. Instead of ‘people will use reusable bags’, it was ‘stores will get around this by using a slightly different bag.’ 

Asking and then what helps us find that when schools ban soda sales households buy more, when communities ban payday lenders pawn shop foot traffic booms, when governments limit cars one day a week the total number of cars rise. 

From, Skipping the Bag: The Intended and Unintended Consequences of Disposable Bag Regulations:

We 􏰂find that plastic bag bans lead retailers to circumvent the regulation by providing free thicker plastic bags which are not covered by the ban. A regulation change that replaced the ban with a tax on all disposable bags generated large decreases in disposable bag use. Our results suggest that plastic bag bans—stricter, but more narrowly defi􏰂ned regulations—􏰁are less effective than market-based incentives on a more comprehensive set of products

There are a cornucopia of incentives to use to change behavior. Sometimes money works well (bag tax). Sometimes social norms work (the authors note that this may be present in their study). The best thing to try might be small bets.