Statistical methods to extract information from SPTs are based on stochastic models, such as the Langevin equation or its Smoluchowski's limit and associated models that account for additional localization point identification noise or memory kernel. The Langevin equation describes a stochastic particle driven by a Brownian force Ξ Ξ and a field of force (e.g., electrostatic, mechanical, etc.) with an expression F ( x , t ) :