You are the project manager for the NHQ Project.

The rough order of magnitude (ROM) estimate is used early in the project when there is not much information available to create a time estimate. Rough order of magnitude estimates can have a range of variance as large as -25% to +75 percent. While ROM is mostly used with cost estimates, it can be used with time estimates too. Rough order of magnitude (ROM), also known as ball park estimate, is a rough approximation, made with a degree of knowledge and confidence that the estimated figure falls within a reasonable range of values. ROM range can vary from half to twice (-50 to +100) the actual cost.

Answer option B is incorrect. Broad estimate is not a valid time estimating type.

Answer option D is incorrect. Expert judgment is what the project manager used in this scenario to create the time estimate, but it is not a time estimating type.

Answer option A is incorrect. An analogous estimate is based on historical information from a similar project. For example, Project A took 8 months to complete and Project B, while similar but larger, will take 10 months to complete.