Insoluble problems in shopping model calibration when the trip pattern is not known

摘要: Openshaw S. (1973) Insoluble problems in shopping model calibration when the trip pattern is not known, Reg. Studies 7, 367–371. Gravity models are often used retail studies to describe or predict turnovers, although few attempts have been made either determine optimum parameter values assess validity of model's performance. Using based on non-linear minimization sum squares differences between predicted and actual sales each centre, it possible show that two Lakshmanan-Hansen Wilson a trivial solution, one versions same reached hidden solution like intervening opportunity version, fail provide an acceptable fit. It suggested basis this evidence no satisfactory can be known therefore observed data urgently required.