... Model.”Journal of the American Statistical Association, 92, 1033–1040.Environmental Protection Agency (1 970 ). The Clean Air Act (CAA); 42 U.S .C. s/s 74 01 et seq.(1 970 ) Clean Air Act and Amendments ... calculate a closed form estimate of the asymptotically exact covariance matrix of the linear component of a GAM (the air pollution coefficients). Furthermore, we developed the S package gam.exact, ... Single-index Models. ” Journal of the American Statistical Association, 92, 477 –489.Chambers, J. M. and Hastie, T. (1992). Statistical Models in S. Chapman and Hall, London.Clancy, L., Goodman, P., Sinclair,...