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THE                      JOURNAL OF ECONOMIC SCIENCES: THEORY AND PRACTICE, V.80, # 2, 2023, pp. 47-59

                    The Augmented Dickey-Fuller test (Dickey and Fuller, 1981) is used to check the
                    stationarity of the variables. Results are presented below:

                    Table 2: ADF test results
                                                  I(0)                            I(1)
                       Indicators
                                       Intercept     Trend and        Intercept       Trend and
                                                      intercept                        intercept

                     RGDPG             -1.906*         -2.376         -7.915 ***       -7.773 ***
                     RNOGDPG           -4.764**      -5.559***        -9.214 ***       -9.312 ***

                     RGOVREV           -2.681*         -2.076        -5.498***        -19.950***
                     RCAPINV            -1.386         -1.109         -4.905 ***       -5.068 ***

                     RTOTTRADE        -3.839***       -3,574**       -4.714***        -4.774***

                     OILPRCG          -6.909***      -6.874***       -8.374***        -8.310***
                                       *
                                **
                     Note:   *** ,    and    denote  statistical  significance  at  1%,  5%  and  10%  level,
                     respectively

                    Source: Compiled by author based on Eviews calculations

                    The specification of the 2 models are presented below:

                               =    +                 −1  +                       −1  +                     −1  +
                                                                       3
                                                     2
                                      1
                                0
                                              −1  +                     −1  + ∑        Δ             −    + ∑        Δ                   −    +
                                                                                 =0
                                                                                      
                                         5
                     4
                                                                 
                                                            =1
                     ∑        Δ                   −    + ∑        Δ                       −    + ∑      =0     Δ                 −    +          (1)
                                                                              
                                                    
                            
                                                                                               
                        =0
                                                =0

                                   =    +                     −1  +                       −1  +                     −1  +
                                   0
                                                                             3
                                                           2
                                         1
                                              −1  +                     −1   + ∑        Δ                 −    +
                                                                 
                                         5
                     4
                                                            =1
                     ∑        Δ                   −    + ∑        Δ                   −    + ∑        Δ                       −    +
                                                     
                                                                            
                             
                        =0
                                                                        =0
                                                =0
                     ∑      =0    Δ                 −    +       (2)
                                              
                            

                    While    , i = 1,...,6 represents long term coefficients,    , i = 1,...,m ,  ,    , i = 1,...,n ,
                             
                                                                                           
                                                                           
                       , i = 1,...,w ,     , i = 1,...,p ,     , i = 1,...,q ,     , i = 1,...,r denote short term
                       
                                                                  
                                                    
                                      
                    coefficients. The symbols m, n, w, p, q, r represents optimal lag lentghs chosen
                    using Akaike info criterion (AIC).

                    EMPIRICAL RESULTS AND DISCUSSION
                    Optimal lags for the models using AIC criterion are presented in the Table 3.

                    Table 3: Selection of optimal models
                     Selected models
                     Model 1                                 ARDL (3,1,0,0,2)
                     Model 2                                 ARDL (4,1,0,4,2)
                    Source: Compiled by author based on Eviews calculations
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