RESUMO
We present a simple method for generating simulated plasmodes and artificial test clusters with user-defined shape, size, and orientation. Our method differs from other cluster generation techniques in that it focuses on the validity of the cluster indicators. For J clusters, indicator validity is defined as the squared correlation ratio between the cluster indicator (i.e., the observed variable) and J-1 dummy variables. The within-cluster correlation structure and the univariate distributions of the cluster indicators are specified with procedures outlined by Fleishman (1978) and Vale and Maurelli (1983). Simulation results illustrate the utility of the method for cluster analysis evaluation research.
RESUMO
Effectance motivation was examined in 26 inner-city children attending Head Start, 26 inner-city children with no preschool experience, and 26 middle-class children attending private preschool. Head Start children scored higher on measures of effectance motivation than did their non-Head Start counterparts; their levels were lower, however, than those of the middle-class children. Implications of the findings are discussed.
