Century scale persistence in longitude distribution: in the Sun and in   silico
  Using Greenwich sunspot data for 120 years it was recently observed that activity regions on the Sun's surface tend to lie along smoothly changing longitude strips 180 degrees apart from each other. However, numerical experiments with random input data show that most, if not all, of the observed longitude discrimination can be looked upon as an artifact of the analysis method. 
J. Pelt, I. Tuominen, J. Brooke