It is imperative to have accurate estimation for cost and time when managing projects because “inaccurate estimates lead to false expectations and consumer dissatisfaction” (Larson and Gary, 2011 pg. 127). There are several techniques project managers can use to estimate the cost and time to complete a project. These techniques can be classified as top-down and bottom-up estimation. Top-down estimates are done by the upper management while bottom-up are done by the executer of the project (Larson and Gary 2011).

The worthiness of any estimation tool depends on several factors. Good planning leads to good estimation. The plan should include all the details needed for the project. Project duration is another factor that plays a great role in the accuracy of estimation. Short project tend to be more accurate than longer projects. Project handlers tend to influence the accuracy of the project. Well- seasonal staff will give better estimation than other staff. The structural organization of the project will influence the accuracy of the estimation. A dedicated team will keep the project on plan and budget. Padding estimate is another factor that influences the accuracy of the project. Organizational culture can influence the accuracy of the estimation some cultures are more tolerant of mistakes (Larson and Gary 2011).

Base on the above mentioned elements, there is no “one size fits all”. Same goes for estimating tools; one cannot say top-down or bottom-up is good tool in all cases and all times. Projects are different from one another. Thus, the nature of the project may require a certain tool vs. another estimation tools.

This is not to say that these tools are perfect, each one has its own pros and cons. Top-down is a good tool to be used when the project still