To investigate the spatial error correlation in panel regression models, various statistical hypothesizes and testings have been proposed. This paper, within introduction to spatial panel data regression model, existence of spatial error correlation and random effects is investigated by a joint Lagrange Multiplier test, which simultaneously tests their existence. For this purpose, joint Lagrang...

Topographic factor is an important factor of computer models of USLE family due to the high sensitivity of model results to its variation and complicated effects of topography on soil erosion. Moore and Wilson (1992) have introduced a well-known method to compute LS factor of RUSLE model using digital elevation model (DEM).The objective of this study was to determine the proper cell size of DEM...