Sandwichman — Of Bathtubs, Bombshells and Boilerplate

The bathtub in question is the analogy Linda Booth Sweeney and John Sterman use to illustrate a dynamic stock-flow system, such as the relationship between greenhouse gas emissions (a flow) and the accumulation of greenhouse gases in the atmosphere (a stock). Gernot Wagner and Martin Weitzman stress the importance of the bathtub analogy in their new book, Climate Shock.

What's fascinating about the bathtub analogy is how consistently people get the dynamics of accumulation wrong. Or at least how often business school graduate students with backgrounds in science, technology, math and economics get it wrong. Sterman has pioneered a cottage industry publishing articles dabout the inability of large numbers of students to correctly identify the effects of flow variations on stock levels. A frequent source of error is something Booth Sweeney and Sterman call "correlation heuristic": students often expect that changes in stock will have the same shape as changes in flow.

This common error has implications for people's attitudes about the action and policy needed to mitigate climate change, Booth Sweeney and Sterman point out. According to the correlation heuristic logic, many people would assume that a reduction in greenhouse gas emissions would directly translate into less greenhouse gas emissions in the atmosphere. It doesn't.....

Econospeak
Of Bathtubs, Bombshells and Boilerplate
Sandwichman