Value for money kills?

Indonesian SODIS users (picture: SODIS Eawag)

Indonesian SODIS users (picture: SODIS Eawag)

SODIS is a cheap method of disinfecting water by putting it in the sun. Like many things, it works better in physics than society, where its effects were not significant, according to a study in PLoS medicine recently. The technical barrier is that people don’t do it much. About thirty two percent of participants in the study used the system on a given day. If you’re familiar with how little things work in reality, this is still surprising. Cheaply disinfecting water seems like it would be a hit with poor people whose children get diarrhea all the time and regularly die. Rural Bolivia, where the study was done, is a good candidate. The children studied usually get diarrhoea four times a year, which causes about fifteen percent of deaths of children under five. For the poorest quintile in Bolivia the under five death rate is about one in ten of those born alive.

The leader of the study, Daniel Mausezahl, suspects a big reason for this is that lining up water bottles on your roof shows your neighbors that you aren’t rich enough to have more expensive methods of disinfecting water. It’s hard to see from a distance the difference between chlorination and coliform-infested jerry cans, so drinking excrement can make you look better than drinking cheap clean water.

Fascinating as signaling explanations are, this seems incredible. Having live descendents is even more evolutionarily handy than impressing associates. What other explanations could there be? Perhaps adults are skeptical about effectiveness? There is apparently good evidence it works though, and there were intensive promotional campaigns during the study. What’s more, lack of evidence doesn’t usually stop humans investing in just about anything that isn’t obviously lethal in the absence of effective means to control their wellbeing. And parents are known for obsessive interest in their children’s safety. What’s going on?

14 responses to “Value for money kills?

  1. Ernie Bornheimer

    My guess is: social stigma is now and real, while harm to the children is not a concern because it’s in the future and might not even happen.

  2. Loss of status is certain – loss of life is less likely.

    Perhaps certainty bias:

    People not admitting the risk of death due to fear? (As in feardie.pdf)

  3. for those who aren’t working under the assumption that the default location for interesting things is Robin Hanson’s home page.

  4. Fascinating! It seems we just do not move into a calculating mode when health is concerned.

  5. Pingback: Overcoming Bias : Pick One: Sick Kids or Look Poor

  6. Measure for Measure

    There’s a distribution of meticulousness in the human population. One third are fastidious (and have sufficient resources): they use chlorination. One third are laid back: they do nothing. The remainder use this system.

    It seems to me that participating in this scheme requires a certain temperament.

  7. agree it’s temperament — there’s all sorts of things people can do all the time that would greatly increase survival rates. most people aren’t great at paying attention to detail, or caring, or believing things like this work, and the poor people who might benefit from this also likely have a large number of other things to deal with that seem equally if not more important. put simply, no mystery at all.

  8. Pingback: Ascription is an Anathema to any Enthusiasm › SODIS - skilling the social engineering

  9. If humans have always had healers/magic men telling them to do apparently nonsensical things then they might be evolved to agree and ignore those recommendations. Much more likely, they simply haven’t evolved a tendency to consider abstract probabilistic and long-term consequences, either memetically or genetically.

  10. What were the explanations offered by the people being studied? It seems far too convenient to assume they’re merely stupid.

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  12. Pingback: i am now paying attention to signals in order to signal | stillgoingnative

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  14. MemeTarget2015

    I have to admit that I subjectively feel there’s something implausible about the effectiveness of ‘disinfect water by leaving it in bottles in the sunlight!’ Maybe one problem with the study is that these Peruvians don’t ‘know to be true’ what someone told them about the treatment method.


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