A major purpose of the progBoth PERT diagrams and Gantt charts are useful to managers concerned with:ramNorthern States Electric is in the process of trying to achieve ISO 14000 certification. Although the criteria for certification involve several milestones, we can be assured they will be evaluated on the regularity and thoroughness of their environmental audits, and how well top management reviews the firm's adherence to policies that are environmentally friendly. evaluation and review technique (PERT) is to identify the minimum time needed to complete a project