Auxological Analysis of Longitudinal Measurements of Human Stature
R. Darrell Bock, University of Chicago,
Stephen H. C. du Toit, University of Pretoria, & David Thissen, University of North Carolina.
Fast, 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
The program 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 output.
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.
Employing Bayesian 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.
Special Features of the AUXAL program
- Program controlled by an easy-to-prepare ASCII command file
- Data may be read from fixed-column or free-column ASCII files
- Free-column fields may be selected from among other fields anywhere in the data record
- Data for successive time points can be on separate records or on one long record
- Observations 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