16 May 2009 • 11:21 am

Numbers, Perception, and Motivation

Reading a post on the excellent political blog, I was reminded that how we look at numbers really affects how we consider the rationale for a proposed change. Congress is currently considering legislation to provide consumers with vouchers of up to $4,500 to scrap their gas-guzzlers and replace them with more fuel-efficient cars.

Here was an excerpt of the proposal:

Light-Duty Trucks: The old vehicle must get 18 mpg or less. New light trucks or SUVs with mileage of at least 18 mpg are eligible for vouchers. If the mileage of the new truck or SUV is at least 2 mpg higher than the old truck, the voucher will be worth $3,500. If the mileage of the new truck or SUV is at least 5 mpg higher than the old truck, the voucher will be worth $4,500.

Wow. It sounds like a windfall for a very slight improvement in gas mileage. But it may be because we are looking at fuel efficiency backwards. Americans evaluate fuel efficiency different than how those do in most other parts of the world.

MPG (miles per gallon) implies that given a fixed amount of gasoline, and we drive as far as we can on that fixed amount. In reality, we usually drive a fixed amount of miles (as a function of commuting patterns to work or school, etc.), and change our driving habits only slightly in response to more plentiful (e.g. cheaper) gasoline.

In Europe and elsewhere, consumers consider the ratio in reverse; quantity of fuel consumed per each fixed distance driven. So let’s use a nice round number of 10,000 miles (roughly the average passenger car distance driven in a year), and consider consumption in GP10kM (gallons per 10,000 miles).

One can save about 100 gallons by upgrading from 18 MPG to 22 MPG, but only about 28 gallons by going from 36 MPG to 40 MPG. This is not a revelation, just a different way of looking at the same information. Watch the four minute video:

The U.S. auto industry has resisted using fuel per unit of distance ratio in favor of distance per unit of fuel ratio to describe fuel efficiency. This may have led to the proliferation of inefficient cars in the U.S. (and perhaps indirectly the stress on the U.S. industry). Researchers at Duke University argue that the EPA should provide consumers with additional GPM information along side MPG when making auto purchase decisions.

What’s the takeaway? Measurement is an important part of motivating people to change. How we present measurements affects perception and behavior. Tenacious change agents in organizations will challenge traditional performance measures and ask what behavior is each measure motivating. Traditional measures promote the status quo, and new measures are needed to drive change.

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