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Estimators create estimates that are “in the middle” — not too high, not too low. The estimate is correct if the estimator feels there is as much chance of going over the estimate as there is of going under. With the measurement capabilities in SPM, if estimators “sandbag” their estimates by constantly estimating high, then as tasks close out that gap will be easily detected in the V1 metric as well as by analyzing the different estimate versus actual metrics within SPM. This differs from the three - point estimation model (optimistic, most likely, and pessimistic estimates) made in traditional project management methodologies (e.g., the Project Management Institute’s PMBOK). The estimator enters only one estimate that represents an estimate for which the team is just as likely to go over the estimate as it is to come in under the estimate. With small task sizes, the volatility metrics — and the numerous metrics to measure both the re-estimating of tasks and the difference between actual hours spent and estimated hours — we don’t need three points of estimation. This simplifies the estimator’s work.
Ref.: PPMO Handbook