Longitudinal factor analysis

A model is presented for factor analysing scores on a set of psychological tests administered as both pre- and postmeasures in a study of change. The model assumes that the same factors underlie the tests on each occasion, but that factor scores as well as factor loadings may change between occasions. Factors are defined to be orthogonal between as well as within occasions. A two-stage least squares procedure for fitting the model is described, and generally provides a unique rotation solution for the factors on each occasion.We thank M. W. Browne, R. P. McDonald, R. Pruzek, and the Managing Editor for their constructive comments.     

Modification of severe disruptive and aggressive behavior using brief timeout and reinforcement procedures

Brief timeout for disruptive and aggressive behaviors and reinforcement for appropriate behaviors were used with two retarded patients in a state hospital ward setting. The procedures reduced loud vocal behavior in one patient and aggressive behavior in another to near-zero levels when first applied. The behaviors returned to previous levels when the procedures were removed and were again greatly reduced when timeout and reinforcement were reapplied. The results were significant because the behavior problems were severe and long-standing and the procedures were instituted without greatly disturbing normal ward routine.