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CPS1853 M. Irsyad Ilham
                In addition to informal testing, there are three formal testing procedures
            that  can  be  used,  namely  Chow  Test  to  choose  between  common  effects
            models and fixed effects models; Hausman test used to select between fixed
            effects  model  and  random  effects  model;  as  well  as  the  Breusch-Pagan
            Lagrange Multiplier (BP-LM) test to choose between common effects models
            and random effects models.
               The test used to check whether FEM better that CEM. This test obtaining
            residual sum square to calculate. The null hypothesis is common effect model
            is better than fixed effect model. The pattern of chow test is
                                          ( − )/( − 1)
                                      =
                                    
                                           ()/( −  − )
            RRSS is residual sum of squares from common effect model. URSS is residual
            sum of squares from fixed effect model. Whether n is number of observation,
            k is number of independent variable, and T is period of time. If F bigger than
             (;−1,−−) , it conclude to reject null hypothesis, which means that fixed
            effect model better than common effect model.
               In  order  to  test  random  effect  model  better  than  fixed  effect  model,
            Hausman test should be used. The null hypothesis of the test state that no
            correlation between individual error and independent variable. In other words,
            the null hypothesis says that random effect model better than fixed effect
            model. The formula is
                                                              2
                                                          ̂
                                              ̂ ′
                                                 ̂
                                     = [ − ]  −1 [ − ]~
                                                              
            Where  is  covariance  matrix  of  −  estimation,  shows  random  effect
                    ̂
                                                   ̂
                                                                ̂
            model regression coefficient vector. The vector  indicate the array of fixed
            effect  model  regression  coefficient.  The  letter  n  and  k  mean  number  of
            observation and number of independent variable. If the value of W bigger than
             2   , it conclude to reject null hypothesis so fixed effect model better than
               (;)
            random effect model.
               To know whether random effect model better than common effect model,
            it  uses  Breuch-Pagan  Lagrange  Multiplier  (LM)  test,  which  developed  by
            Breuch-Pagan. The test base on the value of residual from common effect
            model. The null hypothesis is intercept is not random variable or common
            effect model is better than random effect model. The formula of the test is
                                          ∑   (∑   ̂) 2
                                                        
                                                                2
                               =         [  =1  =1  − 1] ~
                                                                    1
                                    2( − 1) ∑   ∑   ̂ 2
                                                     =1
                                                         
                                                =1
            Where n and T are number of observation and total period of time. The symbol
            ̂ is  residual  from  common  effect  model.  If  the  value  of  LM  bigger  than
             
             2   , it conclude to reject null hypothesis which means that random effect
               (; 1)
            model better than common effect model.
               Building the appropriate panel data regression model from econometric
            criteria, are needed a test and deal with several problems according to the
            model assumption. If the selected model is fixed effect model or common
            effect  model,  the  assumption  which  should  be  full-filled  are  normality,
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