Table 6.

Decomposition analysis of sources of urban sprawl indices.^a

Variables		Ln(ArtifArea)			Ln(Scatt)
	(1)	(2)	(3)	(4)	(5)	(6)	(7)
	Changes in variables (percent)	Estimated parameter	Impact on ArtifArea	Contribution (percent)	Estimated parameter	Impact on Scatt	Contribution (percent)
Ln(POP)	5.36	0.170	0.911	4.96	−0.237	−1.27	14.00
Ln(GDPcap)	68.00	0.210	14.28	77.60	−0.035	−2.38	26.24
Residual				17.44			59.76
ArtifArea	18.40			100
Scatt	−9.07						100

Notes: ^aThe decomposition analysis follows three steps. First, the percentage change of each variable between 1990 and 2000 is calculated (column 1). Then column 1 is multiplied by parameters estimated for each index (columns 2 and 5) to obtain the impact of each time-varying variable on both indices, respectively (columns 3 and 6). Finally, the impact of each variable is divided by the percentage change in ArtifArea (18.4%) and Scatt (−9.07%) to obtain the contribution of each variable to changes in ArtifArea (column 4) and Scatt (column 7).