The estimation process is following.
To find out all requirements a business analyst discusses a project scope with stakeholders and then invites a technical specialist. Engaging a technical specialist at the decomposition stage leads to better and more accurate results.
The project is typically decomposed into smaller components called activities that represent the work to complete.
The activity list includes activity identifiers and the detailed description of work scope. These specified activities provide a basis for project performance at all stages: estimating, scheduling, executing and controlling.
When all the activities are defined, the business analyst and technical specialist sequence the activities using logical relationships and decide on a development path.
The determined and sequenced activities are estimated by the technical specialist and business analyst in work periods, usually days or hours.
During the project execution, the estimate allows measuring project progress against the time baseline and making forecasts.
When the estimate is ready we calculate the project cost