Heagney (2012) also notes that no learning occurs without feedback. Estimate, then monitor the actual time to improve estimation ability. Historical data must be analyzed based on numerous factors, including similarity of projects. Historical data for the construction of a gas station should not be used for the construction of a department store without careful analysis and adjustments based on the complexity of each project. Further analysis is also required for activities affected by weather conditions relative to the expected time of year the work will take place