Estimating plays an important role with the planning process. Prior to start duration and cost estimates, effort hours (man hours) should be computed initially. Pursue the following necessary steps to estimate effort hours.
1. Find out the accuracy of your estimate: As much as your estimate will be perfect, you can gather more detailed information regarding the construction project. While preparing a rough order of magnitude (ROM) estimate (-25% – +75%), it can be completed in quickest possible time with high level, and a lowest amount amount of detail. Alternatively, while executing a exact estimate within 10%, one shoud spend more time and recognize the work at a lower level of detail.
2. Make the preliminary estimate of effort hours: Apply different estimating techniques like analogy, prior history, PERT, modeling, etc. to estimate the project work.
3. (optional) Feature the effort hours on the basis of the allocated resources: If the estimate is performed on the basis of the endeavor involving average resource to execute the project. Sometimes you possess the knowledge of the accurate resource or the nature of resource to be allocated. If you perform, you should need to feature the estimate up or down based on that resource.
4. Include specialist resource hours: You have to ensure that you have choosen hours for part-time and specialty resources. These consist of freelance people, training specialists, administrative help, etc which are essential for special activities. As they belong to project support roles, it may happen that you overlook to take in their activities in the original Work Breakdown Structure.
5. (optional) Put in rework time: In a well organized project, all project deliverables should have been accurate initially. Rework is required if there are any mistakes in your quality management practice. It denotes that a deliverable seems to be perfect turn out to require additional work. Some projects include effort hours for rework, even though this should be curtailed.
6. Affix project management time: Project management acquires effort. A rule of thumb is to include 15% of the effort hours for project management. As for example, if a project estimate involves 12,000 hours (7 – 8 people), then a full-time project manager (1800 hours) is necessary.
7. Include contingency hours: Contingency denotes the insecurity or risk occured with the estimate. While preparing a estimating work which is not defined properly, one may include 50%, 75% or more to reveal the uncertainty. If the estimate is needed on short notice, a large contingency is necessary. Even if get time for preparing a estimate that is logically perfect, your contingency may still be 10-25%. If you do not insert a contingency amount, it suggests that you are 100% self-assured with your estimate. This may happen if the projets with identical nature have been completed earlier.
8. Work out the total effort: Combine the estimates for all the work components explained above.
9. Evaluate and fine-tune as essential: Sometimes while combining all the components, the estimate turns to be noticeably high or low. If your estimate seems to be improper , get back and make corrections to your estimating assumptions to expose reality in a superior manner.
10. Document all assumptions: You will never be familiar with all the details of a project for positive. Therefore, it is essential to document all the assumptions you are producing together with the estimate.
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