There are various Levels of Accuracy used in cost estimating and project planning: Level 1 is at project initiation/initial concept, Level 2 is at Feasibility, Level 3 is at Project Definition/FEED while Level 4 is at Detailed Design. It is recommended that project promoters utilize the services of certified professionals and consultants in the preparation, evaluation, and review of their investments proposals to ensure the credibility of their assumptions, models, and projections.