hausman specification test how is panel data selected what is the impact of a panel data set on bilateral trade? what model should i use for bilateral trade does time series use panel data which model is selected on the basis of hausman specification test how is panel data selected hausman test for panel data why do we use panel data why do people use panel data which model is selected on the basis of hausman test? what is panel data in gravity model what is the base of panel data what is the difference between panel and time series what is the base for selection of the gravity model what is panel data used for? which model is the panel data set in gravity which model is selected on the basis of hausman specification test how is panel data selected in gravity model which is the base of hausman model? what is panel data