Identification and estimation of differential equation models for circadian data (1988) for visualizing data in four or more dimensions (1995) Penguin: A system for graphical data analysis (1992) Additive principle components: A method for estimating equations with small variance from data (1987) Principal curves and surfaces (1984) Interactive graphics for data analysis (1982) Wavelet methods for the inversion of certain homogeneous linear operators in the presence of noisy data (1994) S. Chen