Dear Stata Users,

I have been trying to run an ARDL specification to get short and long-run price elasticity of electricity in the mining sector. But I have come up with a few doubts which I hope you all can help me:

1) All my variables are expressed on log forms, but ln_price is the only variable that is not stationary.
So, I tried three things:
a - try to run d.ln_price as an independent variable but ARDL won't allow it.
b- Run ARDL with the option ec, but ln_price coefficient wasn't reported on the SR box.
c - WORK - I applied the option ec1, and it did report ln_price for SR.

2) Once my models is expressed on logs, can I interpret for the
ardl (variables) ec1
, model,the LR and SR coeficients for ln_price as elasticities.

3) How can I get the results for cusum and cusum6 stability diagnostics.

Thank you all,

Max

Code:
* 2 -  Stationary of each test - ADF
* lags() <-  augumented dickey fuller
* Test statistic (ABSOLUT Value) > Critical value: No unito root - Estcionario : Z9t = 0000

dfuller ln_elect, lags(1)

dfuller ln_price, lags(1) /// Serie still not stationary
dfuller d.ln_price,lags(1) 

dfuller ln_temp, lags(1)
dfuller ln_crush, lags(1)
dfuller ln_grind, lags(1)
dfuller ln_wet, lags(1)
dfuller ln_pipe_day, lags(1)


* 3B - stimate Error correction model - ec
ardl ln_elect ln_price ln_temp ln_crush ln_grind ln_wet ln_pipe_day, maxlags(4) ec aic

* PSS bounds cointegration test: F stat > I(1) long-run convergence - reject H0
estat ectest

* 3C - Estimate Error correction model - ec1
ardl ln_elect ln_price ln_temp ln_crush ln_grind ln_wet ln_pipe_day, maxlags(4) ec1 aic regstore (ecreg)
estat ectest


* ADJ will give me speed of adjustment to equilibrium

* 5 Test diagnostics

estimates restore ecreg
regress
* Autocorrelation
estat dwatson
estat bgodfrey, lags(1)

* Heterocedas
estat imtest, white

* Residuals diagnostics
drop _est_ecreg
predict resid, residuals
jb resid

* Stabiity test
cusum6 elect crush grind wet_route pipe_day, cs(cusum) lw(lower) uw(upper)
drop cusum upper lower
Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input float(ln_elect ln_price ln_temp ln_crush ln_grind ln_wet ln_pipe_day)
7.678326  4.432626 3.2308044  11.39989 11.459258 10.414155  3.178054
7.520776  4.443538  3.182212 11.228124 11.096858  9.877563  3.178054
7.696667 4.4450064  3.164631 11.387753  11.48345  10.20356  3.178054
7.733246 4.4591227  3.166319  11.58878  11.58613 10.545817  3.173472
7.720018 4.3275814  3.110845  11.57683 11.605168  10.58271  3.177417
7.759187 4.4483166  3.135494 11.479693  11.55425   10.5357  3.177012
7.721349  4.772656 3.1380994 11.708186  11.54348 10.398445  3.178054
7.757906  4.769964 3.1671615 11.494227  11.57228  10.61898  3.178054
7.777792  4.833129 3.1152916  11.69004 11.637062 10.725288  3.178054
7.748891  4.923521  3.191299  9.735137 11.620545 10.577422  3.178054
7.795235  4.934645  3.222868 11.877226 11.685922 10.788654  3.178054
7.774015  4.948517 3.2410285  11.88547 11.455106  10.62399  3.178054
7.748891  4.925329 3.1671615  11.44912 11.463077 10.679243  3.176664
7.723562  4.890205 3.2252555 11.365754  11.33602 10.546218  3.177359
 7.72533  4.951154 3.2642314  11.48835 11.474895 10.669333 3.1755044
 7.76811  4.958558 3.2027464 11.456936 11.490775 10.713425  3.178054
7.779885   4.95688  3.161247  11.55528 11.582033 10.795597  3.178054
7.780721  4.950405  3.186353 11.580157 11.538794  10.76372  3.178054
7.292337  4.962177  3.194583 10.680027  10.48253  9.753266  3.178054
7.742402  5.119846   3.17722  11.40593 11.468124 10.736954  3.178054
7.784057  5.106945 3.2108436    11.632 11.519574 10.710258  3.178054
 7.77863  5.142117  3.247269 11.595092 11.608186 10.738464  3.178054
7.771489  5.164707  3.226844 11.571593 11.624661   10.8942  3.178054
7.767687  5.164965  3.254243 11.549816  11.52789 10.743455  3.178054
7.786137  5.159604 3.2642314  11.67709  11.64573  10.93073  3.178054
7.777792  5.152709  3.232384 11.607572 11.631289   10.8507  3.178054
7.380256  5.164719 3.2308044 10.972148 11.030688 10.250584  3.178054
7.771489  5.171672  3.212455 11.543886 11.638063 10.849812  3.178054
7.775276  5.142117  3.255786  11.66251  11.58986  10.72337  3.178054
7.751475  5.206405  3.242592 11.484583  11.53838  10.85212  3.178054
 7.77191  5.164965  3.248823 11.612708 11.551086  10.74789  3.178054
7.750184  5.224658  3.268047 10.817416 11.499332 10.668744  3.178054
7.793174  5.203299 3.1929424 11.869543  11.73974  11.01189  3.178054
7.691657  5.820727  3.185526 11.609912  11.28144 10.471704  3.178054
 7.73587  5.812444  3.174715  11.62338 11.610756  10.87262  3.178054
7.822445  5.846316 3.2027464  11.85509 11.808487 11.021698  3.178054
7.765569  4.993704  3.222071 11.449142 11.646533 10.796683  3.178054
7.787382  4.999664  3.223664  11.79264 11.686836 10.907952  3.178054
7.739359  5.159604  3.256557 11.578225 11.631094 10.877684  3.178054
7.742402  5.846812  3.268047 11.692508 11.612547 10.823917  3.178054
7.762596  6.078221  3.256557  11.39932 11.703413 10.919536  3.178054
 7.76811  6.061313  3.264996 11.708612 11.669996  10.87335  3.175446
 7.79111  6.118196  3.310543  11.86072  11.65515 10.853614  3.178054
7.763871  6.116904  3.269569 11.629745  11.66215  10.86929  3.178054
7.779048  6.105145  3.212455 11.734654 11.696103  10.84091  3.178054
7.798112  6.101893 3.1099534  11.45494 11.781177  11.12029  3.178054
7.778212  6.112237  3.093766 11.734188 11.665723 10.881025  3.178054
7.789868  6.241816  3.151881 11.357883  11.70189 10.915314  3.178054
7.794411  6.236017  3.182212  11.86306 11.595922 10.851686  3.178054
7.781138  6.241921 3.2457125 11.663088  11.52188 10.853637  3.178054
7.768956  6.242009 3.2363226 11.453182  11.55534 10.771102  3.178054
7.467371  6.241375 3.2084215  11.10486  11.05071 10.311498  3.178054
7.773174  6.241234 3.2051826  11.59792 11.577672  10.85604  3.178054
7.774015  6.238722  3.150169  11.65132 11.735893    10.915  3.178054
7.780721  6.127785  3.160399 11.579336 11.629544 10.871556  3.178054
7.669962  6.118447  3.192121 11.527932 11.557766 10.791312  3.119485
7.758334   6.14874  3.162094   11.5705 11.582692  10.67447  3.178054
7.772753  6.158661  3.166319 11.450698 11.670615 10.932143  3.178054
7.798523  6.149483  3.218876 11.815488  11.61465 10.792858  3.178054
7.759187  6.153353  3.218876 10.336456 11.586835 10.760762  3.178054
end




Follows my code and data: