Time Estimation

Estimating techniques: analog, parametric and bottom-up

Estimating the time required for each task requires the application of analytical tools of varying precision.

The analog technique uses historical records of previous efforts with similar characteristics to project the current duration. Although it is fast and inexpensive, its level of accuracy is considerably low.

For greater rigor, the parametric methodology is used, which multiplies known numerical variables to obtain more accurate projections.

For example, if the exact time it takes to pave a kilometer of road is known, it is multiplied by the total length required.

Finally, the bottom-up strategy represents the most exhaustive approach, calculating time from the smallest units to the sum of the entire block.

While this model guarantees unsurpassed accuracy, it demands an extremely high investment of administrative time and is usually reserved for the most critical or financially sensitive requirements.

Three-value estimation (PERT) for greater accuracy

To neutralize the uncertainty inherent in any planning, managers employ probabilistic formulas that contemplate multiple future scenarios.

This methodology requires compiling three time projections for the same activity: an optimistic scenario, a pessimistic scenario and the most likely duration.

By applying mathematical formulas, such as the simple average or the weighted beta distribution, a much more realistic and balanced result is obtained.

In the beta distribution, the most likely scenario receives a higher multiplier weight, reflecting statistical reality.

This analytical rigor is applied as a priority to those actions that have no margin of error, thus protecting the overall schedule.

For example, when importing specialized turbines from another continent, averaging the ideal transit time with possible customs delays will yield a much more certain arrival date, avoiding severe logistical bottlenecks in the assembly chain.

Summary

Determining the exact duration of work requires an intelligent choice between analytical, parametric or bottom-up methodologies. This strategic choice will depend directly on the level of corporate urgency and the accuracy required to ensure compliance.

Operational uncertainty is effectively mitigated by applying mathematical models that consider optimistic, probable and highly pessimistic scenarios. Averaging these three variables generates robust estimates that protect the plan against unforeseen deviations caused by exogenous factors.

Investing greater analytical effort in the truly critical actions is indispensable to shield the viability of the entire project. This mathematical rigor prevents unrealistic commitments, providing management with completely reliable, defensible and executable time projections.