A hierarchical relational definition system (26) for defining an object is provided in which a user is presented with a plurality of menus from which selections are made, whereupon the system references a database (10) to obtain information about an object corresponding to said selections, the data including control data to determine whether a formula is to be referenced to calculate further data, and provides an output including information about said object. The system is useful in cost estimate engineering to provide estimates of man-hours to install materials. The system also has a formula adjustment mechanism (44,46) to refine the formulae according to any variation between the actual man-hours and the calculated man-hours.