“Er … have you ever broken the law?”

July 1, 2011 by Shane Diffily

Ever feel you want to ask an awkward question in an online survey – but think everyone will simply lie in their response?

This article from Scientific American shows how – with a little simple maths – we can get the insights we want.

Broken love

Example…

“Have you ever cheated on your husband / wife?” … YES or NO.

Before your respondent answers you simply ask them to privately flip a coin – but (this is the important bit) they must not tell anyone how the coin lands.

  • If it lands ‘heads‘, they just click ‘YES’ no matter if they have cheated or not.
  • If it lands ‘tails‘, they should answer truthfully.

To see how we can then find the right distribution of YES and NOs, just read the article.

It’s short, brilliantly simple and potentially very useful for some types of online survey.

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