  The study of collective decision making system has become the central part of
the Swarm- Intelligence Related research in recent years. The most challenging
task of modelling a collec- tive decision making system is to develop the
macroscopic stochastic equation from its microscopic model. In this report we
have investigated the behaviour of a collective decision making system with
specified microscopic rules that resemble the chemical reaction and used
different group size. Then we ventured to derive a generalized analytical model
of a collective-decision system using hyper-geometric distribution.
  Index Terms-swarm; collective decision making; noise; group size;
hyper-geometric distribution
