Tax revenue mobilization effort in Southern African Development Community (SADC) bloc: Does ICT matter?

Figures & data

Table 1. Fisher-Augmented Dickey Fuller (ADF) and Philip-Perron (PP) unit root tests

Variables	Fisher-ADF Test		PP-Fisher Test
	Chi2	Chi2	Chi2	Chi2
	Level I(0)	1^st Difference I(1)	Level I(0)	1^st Difference I(1)
TAXR	25.0044	75.5313*	37.1520**	125.338*
TAXGS	28.3759	63/6423*	49.7528*	126.545*
TAXC	23.3533	65.5930*	25.4500	102.473*
INTUSER	39.4312**	31.3808	31.7365	63.6282*
MOBILE	14.0217	85.3819*	2.3793	96.3350*
GDPCG	37.0704**	63.8641*	81.9039*	229.323*
URBG	28.8464	55.7255*	45.3845*	166.553*
TRADE	17.8843	58.9570*	21.0802	156.845*
CONT	60.1504*	43.3108*	116.467*	146.708*
LFPR	22.1857	41.7172*	45.6883*	63.5643*

Note: * and ** represent 1 and 5 percent level of statistical significance

Source: Authors’ computation extracted from EViews 12

Table 2. Kao (Engle Cointegration Test)

Series	ADF
	t-Statistic	Prob. value
TAXR, INTUSER, GDPCG, URBG, TRADE, CONT, LFPR	−7.2763	0.0000
TAXR, LMOBILE, GDPCG, URBG, TRADE, CONT, LFPR	−6.4294	0.0000
TAXGS, INTUSER, GDPCG, URBG, TRADE, CONT, LFPR	−6.6569	0.0000
TAXGS, LMOBILE, GDPCG, URBG, TRADE, CONT, LFPR	−6.2935	0.0000
TAXC, INTUSER, GDPCG, URBG, TRADE, CONT, LFPR	−4.1024	0.0000
TAXC, LMOBILE, GDPCG, URBG, TRADE, CONT, LFPR	−3.5455	0.0002

Note: Log transformation of mobile cellular subscription (LMOBILE) was used in all the models

Source: Authors’ estimation (extracted from EViews12)

Table 3. Fully modified OLS regressions results

Variables	A: TAXR MODEL		B: TAXGS MODEL		C: TAXC MODEL
	Model I	Model II	Model I	Model II	Model I	Model II
Interuser	0.042*** (0.023)	——	0.050** (0.023)		0.177* (0.061)
Lmobile	——	0.050** (0.123)	——	0.175*** (0099)		0.795*** (0.424)
Gdpcg	0.313* (0.070)	0.072** (0.011)	0.144* (0.046)	0.188* (0.045)	0.924* (0.187)	1.088* (0.193)
Urbg	1.432*** (0.855)	0.227*** (0.130)	0.654 (0.582)	0.425 (0.569)	6.834* (2.286)	5.417** (2.392)
Trade	0.121* (0.024)	0.007** (0.004)	0.012 (0.016)	−0.005 (0.016)	0.120*** (0.064)	0.033 (0.069)
Cont.	−0.042 (0.102)	0.023 (0016)	0.086 (0.068)	0.031 (0.068)	0.466*** (0.273)	0.287 (0.289)
Lfpr	0.178* (0.045)	0.020** (0.007)	0.067 (0.029)	0.064** (0.030)	0.247** (0.120)	0.248 (0129)
No. of observation	169	173	164	168	169	173
Adj. R^2	0.864	0.568	0.818	0.795	0.793	0.737
Wald test	104.48 (0.000)	112.45 (0.000)	30.58 (0.000)	37.24 (0.000)	61.32 (0.000)	66.39 (0.000)

Note: *,** and *** represent 1, 5 and 10 percent level of significance respectively

Log transformation of mobile cellular subscription (LMOBILE) was used in all the models and results are interpreted accordingly.

Standard errors are reported in bracket along with the estimated coefficient of each variable

Probability value of the Wald test Chi² statistic is reported in bracket