Heagney (2012) also finds that no learning takes place without feedback. Estimate, then track real-time to improve estimation capability. Historical data must be analyzed based on many factors, including project similarity. Historical data for the construction of a gas station should not be used for the construction of a large warehouse without careful analysis and adjustments based on the complexity of each project. Additional analysis is also required for activities affected by weather in relation to the anticipated time of year the work will be carried out.