DEA Malmquist productivity index based on a double-frontier slacks-based model: Iranian road safety assessment

European Transport Research Review

An Open Access Journal

Table 2 Correlation matrix of all variables

Variables	Police Station (PS)	Road Maintenance Depot (RMD)	Equipment & Vehicles (E&V)	Camera (C)	Emergency Medical Service (EMS)	Road with Lighting System (RLS)	FR ^-1
a) 2014
Police Station (PS)	1	0.830^**	0.758^**	0.727^**	0.923^**	0.858^**	0.798^**
Road Maintenance Depot (RMD)		1	0.788^**	0.643^**	0.797^**	0.638^**	0.722^**
Equipment & Vehicles (E&V)			1	0.659^**	0.658^**	0.619^**	0.571^**
Camera (C)				1	0.659^**	0.736^**	0.718^**
Emergency Medical Service (EMS)					1	0.798^**	0.838^**
Road with Lighting System (RLS)						1	0.733^**
FR⁻¹							1
b) 2015
Police Station (PS)	1	0.821**	0.764**	0.796**	0.914**	0.863**	0.809**
Road Maintenance Depot (RMD)		1	0.790**	0.578**	0.795**	0.647**	0.766**
Equipment & Vehicles (E&V)			1	0.573**	0.676**	0.651**	0.626**
Camera (C)				1	0.673**	0.860**	0.670**
Emergency Medical Service (EMS)					1	0.777**	0.887**
Road with Lighting System (RLS)						1	0.702**
FR⁻¹							1
c) 2016
Police Station (PS)	1	0.814**	0.796**	0.895**	0.916**	0.867**	0.663**
Road Maintenance Depot (RMD)		1	0.791**	0.695**	0.789**	0.646**	0.653**
Equipment & Vehicles (E&V)			1	0.559**	0.655**	0.660**	0.394*
Camera (C)				1	0.837**	0.866**	0.696**
Emergency Medical Service (EMS)					1	0.788**	0.744**
Road with Lighting System (RLS)						1	0.585**
FR⁻¹							1