in thr name of God Hi Dear i try to test unit root of eff1 in my panel data = data1 but this is the eroor what should i do ? purtest(eff1~1,data=data1,index="indu",pmax=4,test="levinlin") Error in purtest(eff1 ~ 1, data = data1, index = "indu", pmax = 4, test "levinlin") : the individual dimension is undefined [[alternative HTML version deleted]]