Saturday, November 12, 2011

Cause and Effect - Non Linear Systems

Here are three examples where cause and effect do not appear to corroborate. Take a look.

  1. Build a flyover on a busy road hoping that traffic will ease – A personal experience [Traffic will actually increase with flyover] 
  2. Dip a thermometer in boiling water. What happens to temperature reading? – Adopted from Gerald Weinberg’s Book “Introduction to General Systems Thinking” [Thermometer will show a lower temperature reading due to difference in thermal expansion between mercury and enclosing glass tube] 
  3. Making Cars more safer will cause drivers to become more aggressive and rash – “Peltzman Effect” Adopted from freakonomics post "What happens to your head” 
 In each of these cases – the effect or what is expected is not what happens – but the opposite. There can be explanations – lesson for testers : think holistically, develop systems thinking mind.

Why this happens? I think we often approach in terms of or use analytical/reductionist thinking - just bread/divide a thing into its constituents (atoms) and study them. This linear thinking of single cause-effect (taken one at a time usually) can help understand some aspects an object/phenomenon. With non linear systems such as societies, political/cultural systems, business systems etc - this simple cause-effect thinking simple does not hold good. So - think in terms of systems and their interactions.