What are black swans and what have they got to do with planning?
The term ‘back swan’ is a metaphor for a highly improbable event, and is derived from the previously held assumption that ‘all swans were white‘ until the discovery of black swans in Australia. The term ‘black swan’ then came to connote an occurrence or an event which was previously assumed to be impossible. (Nassim Taleb) The concept is not a new one. In economics, such black swan events are known as outliers, in that they sit outside the range of typical occurrences spread around a mean.