Limit order market analysis and modelling: on an universal cause for   over-diffusive prices
  We briefly review data analysis of the Island order book, part of NASDAQ, which suggests a framework to which all limit order markets should comply. Using a simple exclusion particle model, we argue that short-time price over-diffusion in limit order markets is due to the non-equilibrium of order placement, cancellation and execution rates, which is an inherent feature of real limit order markets. 
Damien Challet and Robin Stinchcombe