4STEPHEN C.Traffic prediction using multivariate nonparametric regression[J].Journal of Transportation Engineering,2003,129(2):161-168.
5Stock J H, and Watson M W. Diffusion indexes [R]. NBER (National Bureau of Economic Research) Working Paper, 1998, No. 6702.
6Stock J H, and Watson M W. Macroeconomic forecasting using diffusion indexes [J]. Journal of Business and Economic Statistics, 2002a, 20(2): 147-162.
7Bai J, and Ng S. Confidence intervals for diffusion index forecasts and inference for factor-augmented regressions [J]. Econometrica, 2006a, 74(4): 1133-1150.
8John M Bonham. A diffusion index approach [J]. Journal of Regional Science, 1975, 15(1): 73 80.
9Valavanis S. Must the diffusion index lead? [J]. The American Statistician, 1957, 11: 12-16.