Downscaling of Open Coarse Precipitation Data through Spatial and Statistical Analysis, Integrating NDVI, NDWI, Elevation, and Distance from Sea

Table 3

Regression parameters of stepwise regression models versus multiple regression models.

(a) Correlation, standardized and unstandardized coefficients

Models	Years		Sig.	Unstandardized coefficients				Standardized coefficients
				NDVI	NDWI	Distance	Elevation	NDVI	NDWI	Distance	Elevation
Group 1: multiple regression models	1999	0.78	0.000	802	307	−0.11	0.07	0.67	0.13	−0.09	0.30
	2000	0.80	0.000	953	166	−0.03	0.05	0.79	0.06	−0.02	0.22
	2001	0.83	0.000	1344	635	−0.05	0.08	0.70	0.18	−0.03	0.22
	2002	0.84	0.000	1253	258	−0.12	0.10	0.74	0.07	−0.08	0.32
	2003	0.85	0.000	1216	401	−0.11	0.07	0.75	0.13	−0.05	0.20
	2004	0.82	0.000	1211	787	−0.05	0.09	0.65	0.22	−0.02	0.23
Group 2: stepwise regression models	1999	0.78	0.000	802	307	−0.11	0.07	0.67	0.13	−0.09	0.30
	2000	0.81	0.000	961	178	—	0.05	0.79	0.07	—	0.21
	2001	0.83	0.000	1355	654	—	0.08	0.71	0.18	—	0.21
	2002	0.84	0.000	1253	258	−0.12	0.10	0.74	0.07	−0.08	0.32
	2003	0.85	0.000	1216	401	−0.11	0.07	0.75	0.13	−0.05	0.20
	2004	0.83	0.000	1221	817	—	0.09	0.65	0.23	—	0.22

(b) AIC and statistical tests

Models	Years						Tolerance				AIC
		NDVI	NDWI	Distance	Elevation	Sig.	NDVI	NDWI	Distance	Elevation
Group 1: multiple regression models	1999	30.77	5.80	−4.65	15.03	0.000	0.530	0.514	0.609	0.628	9557
	2000	38.30	3.04	−1.12	11.99	0.263	0.514	0.532	0.611	0.670	9536
	2001	31.51	8.04	−1.41	13.15	0.159	0.392	0.394	0.626	0.703	10247
	2002	37.30	3.64	−4.34	19.30	0.000	0.469	0.456	0.582	0.672	9843
	2003	29.71	4.91	−3.18	12.80	0.002	0.273	0.267	0.603	0.711	10146
	2004	26.88	8.85	−1.21	4.89	0.228	0.344	0.317	0.572	0.669	10445
Group 2: stepwise regression models	1999	30.77	5.80	−4.65	15.03	0.000	0.530	0.514	0.609	0.628	9557
	2000	39.90	3.32	—	13.63	—	0.550	0.554	—	0.964	9524
	2001	32.36	8.39	—	14.63	—	0.407	0.405	—	0.980	10205
	2002	37.30	3.64	−4.34	19.30	0.000	0.469	0.456	0.582	0.672	9843
	2003	29.71	4.91	−3.18	12.80	0.002	0.273	0.267	0.603	0.711	10146
	2004	27.13	9.58	—	15.27	—	0.347	0.345	—	0.976	10441

Sig.: signification test of distance from sea at 2-tailed .