Dice Help Scientists Get Honest Answers to Touchy Questions

80beatsBy Veronique GreenwoodAug 3, 2011 12:58 AM


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New tools for conservation?

What's the News: Maybe it's you---or maybe it's the dice. A technique that relies on concealing individual transgressions while revealing greater truths is letting biologists get to the bottom of South African farmers' killing of leopards

. What's the Context:

  • In South Africa, there's constant tension between carnivores and local farmers, who may kill animals they perceive as a threat to livestock.

  • Knowing whether farmers are doing this helps conservationists understand the driving forces behind animals' extinction and plot countermeasures, but since killing carnivores like leopards and brown hyenas is illegal, it's hard to get a straight answer from farmers about their activities.

  • Enter the randomized response technique, which was first developed in 1965. Also used by social scientists to get people to talk about their sex lives, it lets researchers see overall trends in taboo behavior without being able to pin a crime or an embarrassing behavior on any one person.

How the Heck:

  • First, a researcher gave a farmer a die, which the farmer could roll without the researcher seeing its outcome.

  • Then, the researcher asked questions like "In the last 12 months, did you kill any leopards?," and before the farmer answered, he rolled the die. If he rolled a 1, he should say "no," no matter what the correct answer was, and say "yes" if he rolled a 6. For all the other numbers, he should answer honestly. The fact the researcher never had any way of knowing whether the farmer was saying "yes" because it was the truth or because he rolled a 6 gave the subject a sense of safety.

  • But after recording all the answers provided by their subjects, the researchers found that farmers said they had killed leopards far more frequently than one in six times, which is what would have been expected had they only admitted to the crime when the die made them. Under the cover of the die, farmers were admitting to having killed the creatures.

  • In fact, judging from the results, at least 19% of the 99 subjects had killed leopards in the last year. That's quite a bit more than researchers were expecting.

The Future Holds: These results will influence conservationists' approaches in the future. For instance, now that they can see how strongly farmers believe leopards are a threat to livestock, they can work to instate programs that replace lost cattle after leopard attacks, perhaps reducing local hostility. But it's not clear that the technique will remain useful for other, similar projects once people know how it works, or whether people in rural areas who hold particular grudges against government interference will play by the rules of the game. They might, after all, just reply randomly. Reference: St. John et al. Identifying indicators of illegal behaviour: carnivore killing in human-managed landscapes. Published online before print July 27, 2011, doi: 10.1098/rspb.2011.1228

Proc. R. Soc. B [via New Scientist


Image courtesy of topher76 / flickr

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