Which type of estimate is known for being made without detailed engineering data?

The type of estimate recognized for being made without detailed engineering data is an Order of Magnitude Estimate. This type of estimate is usually prepared during the early stages of project planning, often based on limited information and historical data rather than comprehensive engineering analyses. It provides a very rough estimate of project costs typically expressed as a range, reflecting the high level of uncertainty in the accuracy of such an estimate.

Order of Magnitude Estimates are particularly useful during initial project evaluations when decision-makers need a quick understanding of potential costs. Given their reliance on broad assumptions and general factors rather than detailed calculations, this type of estimate is expected to have a significant margin of error— often around plus or minus 50%. This contrasts with more precise estimates that come later in the project lifecycle, where detailed engineering data is available.

In contrast, Definitive Estimates, Budget Estimates, and Contingency Estimates all utilize varying levels of detail and data, often incorporating more substantial empirical inputs to refine cost projections as a project matures. Definitive Estimates are based on extensive detail and project specifications, whereas Budget Estimates provide a more refined tool for project funding but still require more data than an Order of Magnitude Estimate. Contingency Estimates specifically focus on allocation for unforeseen costs but hinge on estimated project