For analyzing samples of curves, Kneip and Gasser proposed a
“structural analysis” for estimating an average curve which gives
the average amplitude and dynamics of the sample curves. An important step of
their method is the estimation of the warping functions in order to eliminate
the differences in dynamics between different curves. It is of interest to
compute confidence bounds for the structural average curve. First, we derive
the necessary asymptotic results to obtain confidence intervals based on
asymptotic normality. Due to the complex form of the asymptotic formulas and
due to their asymptotic nature, bootstrap procedures are studied in a second
step. A small archive SACI (Structural Averaging and Confidence Intervals),
written in Fortran, can be obtained from the Web site
“http://www.unizh.ch/biostat” to compute the structural average
curve, to construct confidence regions at a structural point and to compute
confidence bars at other points.