Analysis of Longitudinal Measurements of Human Stature
Bock, University of Chicago,
Stephen H. C. du Toit, University of Pretoria,
& David Thissen, University of North Carolina.
comprehensive analysis of data from longitudinal growth studies is now
available on your desktop with the AUXAL program from SSI.
Structural Analysis with the BTT Model or the JPA2 Model
Nonstructural Analysis by Fourier Transform of Residuals
or Kernel Smoothing
performs both structural and nonstructural auxological analysis of human
growth in standing height or recumbent length. It provides accurate fitting or
smoothing of growth curves for height, velocity, and acceleration and displays
the height and velocity curves in publication quality graphic
Maxima and minima
of velocity are located and described. Data from multiple cases can be
analyzed in one pass through the program and the results summarized both
longitudinally and cross-sectionally.
methods of estimation, the program is able to fit the structural models to
incomplete longitudinal data. This facility makes it possible to estimate a
structural average curve for the full growth cycle from mixed longitudinal
data consisting of a sample of short studies beginning at random ages. It also
makes possible the prediction of height at maturity, or any other age, from
one or more measures of height prior to maturity.
of the AUXAL program
controlled by an easy-to-prepare ASCII command file
- Data may be
read from fixed-column or free-column ASCII files
fields may be selected from among other fields anywhere in the data
- Data for
successive time points can be on separate records or on one long
may be selected by age or height ranges in each case
- Cases from a
large study may be selected or omitted as specified on a supplied list
analysis with the Bock-Thissen-du Toit (BTT) model or the
Jolicoeur-Pontier-Abidi (JPA2) model.
analysis by the Gasser-Müller optimal kernel for smoothing of distance,
velocity, and acceleration, or by Fourier analysis of residuals from either
of the structural models.
description of maxima and minima of the growth velocity curve of each case
and of the structural average curve.
- Maximum a
posteriori (MAP) fitting of the structural models assuming autocorrelated or
uncorrelated residuals. Estimation of the root mean square error after
fitting or smoothing individual case data.
- Estimation of
the generalized distance of each case from the population centroid of the
structural model parameters.
detail listings including observed heights, empirical velocities, fitted or
- Sample problem
input and output.
appendix on structural and nonstructural analysis of multiphasic
means, standard deviations, standard errors, skewness and kurtosis for
height and velocity and height and velocity residuals.
- Sample means,
covariances and correlations of the estimated parameters of the structural
- Sample means of
the Fourier coefficients.
percentiles of the sample distributions of height and velocity.
- Summary of age,
height, and velocity at the velocity maxima and minima of all cases in the
- Analysis of the
sample structural average curve.
- The plotting
facility selects, displays and prints individual growth curves for height
- Velocity maxima
and minima identified on the plots.
A 170-page User's
- Introduction to
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