Analogous and parametric estimating
Use comparable historical work or a defensible quantity-rate relationship to estimate new work.
Reference · Guide · Foundation
Explain an uncertain estimate
Define scope, units and the evidence behind the range.
Understand
Estimate maturity and uncertainty
Explain how scope definition, evidence and estimation method affect the confidence in an estimate.
Reference · Guide · Foundation
Estimate with a range
Discuss distinct scenarios before calculating a weighted average. The explanation for the range is often more useful than the middle number.
Method · Calculator + guide · Applied
Estimating techniques by stage
Fit the technique to the stage and the data, and show how wide the estimate still is.
Model · Study sheet · Foundation
Software size and effort estimation
Keep product size, team-relative effort and elapsed duration distinct.
Reference · Guide · Foundation
Three-point estimate (PERT)
Replace a single guess with a range: an expected value and a spread that show how sure the estimate is.
Model · Study sheet · Foundation
Three-point estimation
Use optimistic, most likely and pessimistic estimates to make uncertainty explicit.
Formula · Guide · Applied
Original sources
Reference class forecasting
Challenge an estimate using outcomes from a defensibly comparable class of completed projects.
Framework · Source pointer · Foundation