Wednesday, April 15, 2009

Story of Stuff - Sustainability and Statistics

I was recently introduced to this interesting video on the history of stuff (~21 min) and thought it might be helpful to do a quick review. I think there are some brilliant messages here, but at the same time, I think this is a prime example of having to look more closely at statistics and question what's presented. First let's look at some of the key points:
  • Linear systems are not sustainable (and certainly cannot support exponential growth). You need a cyclic system in order even have a chance.
  • Externalizing costs is a model which offsets the factors of production to keep costs low (and like over utilizing any resource is itself unsustainable).
  • The three R's are Reduce, Reuse, Recycle (in that order). Recycling should actually be a last resort from a sustainable consumption perspective.
While I like the overall message, I find some of the points and use of statistics questionable. Or as xkcd puts it:

For instance, Anne Leonard states that 99% of everything we consume is disposed of in 6 months. That's a lot. I have a general heuristic for these types of scenarios. If your statistic produces a result of more than 90%, that generally means there is some selective data mining going on. To reach a number like 99%, it suddenly becomes more interesting as to define what is the 1% that we keep beyond 6 months. It seems pretty astronomical, yet something about this doesn't seem right. What could possibly justify this number?
  • Why six months? Why not look at a quarter? A year?
  • Is it measured by income dollars spent? Mass of goods? Volume occupied in a landfill versus in storage?
  • What's included? Housing, food, gasoline, seasonal clothes, books, text books per semester, garbage?
  • What would be a more appropriate number given the same metrics? What should we aim for?
Next, Anne mentions that the US has 5% of the worlds population but they are consuming 30% of the resources (implying a footprint of 6x of what is should be). She also mentions that we are consuming 2x as much as 50 years ago which I feel is like comparing our peek consumption with our valley (which upon further analysis is almost meaningless). 50 years ago is very close to the depression and WWII which are the lowest consumption rates in recent history.

I am very opposed to peak to trough comparisons in behavioural studies because they represent extremes. I'd be more impressed with a normalized study over time with standard deviations rather than an opportunistic snapshot of a scenario 50 years earlier. This is because I'd expect that despite the growth of consumption, there is a corresponding diminishing utility that Anne hints at as a cause of decreased happiness since the 50s.

Her point on computers and planned obsolescence is both correct in many respects yet highly oversimplified and as a result (I would suggest) misleading. She implies that a computer upgrade is simply a CPU replacement and that companies intentionally design chips so that they cannot be easily substituted.

Upgrading a computer can *sometimes* be as simple as replacing a chip, but often with increases processing power come increases in bus speed and memory. A computer system is a much more complicated than simply replacing an old chip with a newer, better one. It's not just a matter of "shape" as suggested. Actually, the change in shape is deliberate to prevent people who don't understand how computers work from blindly substituting in parts (and destroying both).

Despite my negative tone regarding her use of statistics, I really think Anne has done something phenomenal. Her attempts to reach a broad audience are successful, but she does sacrifice a bit of credibility for accessibility. Some of her broad and extreme claims leave her work more vulnerable to criticism than it should be. I do like her proposed solutions, but I think the corresponding required change in consumer behaviour will be quite a challenge. I think that everyone should spend the just 21 minutes and watch this video.

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