Hello.

I am using xtgcause command for granger causality analysis.

I have a dataset for gdp growth and housing prices that looks like this

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input str3 code str7 time float(gdp_value hp_value)
"NLD" "2005-Q1"   .322858  120.8404
"NLD" "2005-Q2"    .70347 121.14498
"NLD" "2005-Q3"  1.342952 121.52393
"NLD" "2005-Q4"   .630551 122.07548
"NLD" "2006-Q1"   .623938 121.92136
"NLD" "2006-Q2"  1.497031 123.00626
"NLD" "2006-Q3"   .598153 123.21648
"NLD" "2006-Q4"     .8245 124.73105
"NLD" "2007-Q1"  1.145697 125.23947
"NLD" "2007-Q2"   .511647  125.9286
"NLD" "2007-Q3"  1.117502 127.33276
"NLD" "2007-Q4"  1.353024 127.85272
"NLD" "2008-Q1"   .327531   126.555
"NLD" "2008-Q2"   .492587  126.6092
"NLD" "2008-Q3"  -.122148 127.45116
"NLD" "2008-Q4"  -.659941   126.312
"NLD" "2009-Q1" -3.593641 125.50623
"NLD" "2009-Q2"   .002509 123.75813
"NLD" "2009-Q3"   .400708  121.3588
"NLD" "2009-Q4"   .602328 121.06926
"NLD" "2010-Q1"  -.181172 119.73282
"NLD" "2010-Q2"   .430196  119.9887
"NLD" "2010-Q3"   .429435 118.35582
"NLD" "2010-Q4"  1.130277 117.32396
"NLD" "2011-Q1"    .59237 116.83125
"NLD" "2011-Q2"  -.094369 115.03316
"NLD" "2011-Q3"  -.008004 113.31206
"NLD" "2011-Q4"  -.596028 111.14565
"NLD" "2012-Q1"  -.216573  108.9804
"NLD" "2012-Q2"   .064111 107.28593
"NLD" "2012-Q3"  -.426776 102.23032
"NLD" "2012-Q4"  -.708357 101.78844
"NLD" "2013-Q1"   .327541  98.08289
"NLD" "2013-Q2"  -.180949  96.39162
"NLD" "2013-Q3"   .605075  96.21662
"NLD" "2013-Q4"   .633838  96.30658
"NLD" "2014-Q1"  -.099695  95.78539
"NLD" "2014-Q2"   .585676  96.76814
"NLD" "2014-Q3"   .252766  96.58524
"NLD" "2014-Q4"   .900677   97.6215
"NLD" "2015-Q1"   .589031  99.25961
"NLD" "2015-Q2"   .316472  99.47125
"NLD" "2015-Q3"   .339938  100.1688
"NLD" "2015-Q4"   .016386 101.10033
"NLD" "2016-Q1"   .906044 102.56538
"NLD" "2016-Q2"   .220417  103.2975
"NLD" "2016-Q3"  1.145374 105.19594
"NLD" "2016-Q4"   .860028 106.61266
"NLD" "2017-Q1"   .490426 107.79723
"NLD" "2017-Q2"   .909608 109.81923
"NLD" "2017-Q3"   .690211 111.25238
"NLD" "2017-Q4"   .789482 114.22588
"NLD" "2018-Q1"   .575801 116.01057
"NLD" "2018-Q2"   .688609 117.69238
"NLD" "2018-Q3"   .265952 120.07318
"NLD" "2018-Q4"    .54636 121.69694
"NLD" "2019-Q1"   .484991 122.44673
"NLD" "2019-Q2"   .326844  124.3768
"NLD" "2019-Q3"   .418324  124.5507
"NLD" "2019-Q4"   .389318 126.31741
end


For each country, there are 60 observations, starting from 2005 q1 to 2019 q4.

The results look like this for Netherlands when I use 4 lags

Code:
. xtgcause gdp_value hp_value, lags(4)


Dumitrescu & Hurlin (2012) Granger non-causality test results:
--------------------------------------------------------------
Lag order: 4
W-bar =          3.9732
Z-bar =         -0.0095   (p-value = 0.9925)
Z-bar tilde =   -0.0649   (p-value = 0.9483)
--------------------------------------------------------------
H0: hp_value does not Granger-cause gdp_value.
H1: hp_value does Granger-cause gdp_value for at least one panelvar (country).
The results look like this when I use aic and big criteria. Here, the value of z bar is significant but not for z bar tilde.

Code:
. xtgcause gdp_value hp_value, lags(aic)


Dumitrescu & Hurlin (2012) Granger non-causality test results:
--------------------------------------------------------------
Optimal number of lags (AIC): 18 (lags tested: 1 to 18).
W-bar =         97.5175
Z-bar =         13.2529   (p-value = 0.0000)
Z-bar tilde =    1.4734   (p-value = 0.1407)
--------------------------------------------------------------
H0: hp_value does not Granger-cause gdp_value.
H1: hp_value does Granger-cause gdp_value for at least one panelvar (country).

. xtgcause gdp_value hp_value, lags(bic)


Dumitrescu & Hurlin (2012) Granger non-causality test results:
--------------------------------------------------------------
Optimal number of lags (BIC): 18 (lags tested: 1 to 18).
W-bar =         97.5175
Z-bar =         13.2529   (p-value = 0.0000)
Z-bar tilde =    1.4734   (p-value = 0.1407)
--------------------------------------------------------------
H0: hp_value does not Granger-cause gdp_value.
H1: hp_value does Granger-cause gdp_value for at least one panelvar (country).

Which one should I use for interpreting the causal relationship? Z bar or Z bar tilde?

Please help!