* * Dougherty, Introduction to Econometrics, 4th ed * Example from Section 13.3 * Graphical analysis of non-stationary series * open data demand.xls calendar(a) 1959:1 data(format=xls,org=columns) 1959:01 2003:01 adm book busi clot date dent doc dpi flow food furn gas gaso $ hous legl mags mass opht padm pbook pbusi pclot pdent pdoc pflow pfood pfurn pgas pgaso phous plegl $ pmags pmass pop popht prelg ptele ptob ptoys ptpe relg tele time tob toys tpe * set logdpi = log(dpi) * graph(footer="Figure 13.20 Logarithm of DPI 1959-2003") # logdpi @acf(method=yule,number=20,$ footer="Figure 13.21 Sample correlogram of log DPI") logdpi * set dlogdpi = logdpi-logdpi{1} graph(footer="Figure 13.22 Differenced Logarithm of DPI 1959-2003") # dlogdpi @acf(method=yule,number=20,$ footer="Figure 13.23 Sample correlogram of differenced log of DPI") dlogdpi