Notes that presence of heterogeneous regression slopes in an analysis of covariance design is equivalent to presence of interaction in randomized-blocks design. Describes modification of the usual graphical representation of heterogeneous regressions that can aid in interpreting significant regions for regression surfaces. (NB)

A study was conducted to determine the effect of graphic format--bar, line, table, and line-table graph--on the interpretation of numerical data by field dependent and field independent students. Ninety-six undergraduate students were given the Group Embedded Figures Test and randomly assigned to one of four treatments. During the testing phase,…