Initial assumptions related to the service life of a particular item, such as a component section of a building, are mathematically modeled to construct an initial lifecycle condition relationship as condition index (CI) v. time. To update the model, empirical data may be input at any time. As modeled in an engineering management system, for example, inspections are performed on the item to verify actual condition with that predicted. Quantitative inspection data are then used to update the initial curve. As inspections are performed and data recorded, the curve is updated to accurately capture observed condition and provide realistic estimates of predicted condition, and expected service life. In select embodiments of the present invention, empirical data, such as that from inspections, are weighted, e.g., inspection data may be weighted based on type, level of detail, time in service, time since last inspection and the like.