  We propose a simple model that describes the dynamics of efficiencies of
competing agents. Agents communicate leading to increase of efficiencies of
underachievers, and an efficiency of each agent can increase or decrease
irrespectively of other agents. When the rate of deleterious changes exceeds a
certain threshold, the economy falls into a stagnant phase. In the opposite
situation, the economy improves with asymptotically constant rate and the
efficiency distribution has a finite width. The leading algebraic corrections
to the asymptotic growth rate are also computed.
