Figure 1.

Change scores by test. The average difference scores for these six tests are generated by subtracting the performance score “after” from “before” surgery or the coronary procedure for all tests except Trails A and B, where just the reverse subtraction is performed. In this way, positive values indicate improved performance. The error bars represent the standard error of the mean (S.E.M.). The two groups are represented by this bar graph: solid black bars, the control group; and vertical striped, carotid endarterectomy (CEA)-regional group.