Can Estimates Make a Projects Fail?

Estimates are as defined by Larson & Gray as "process of forecasting or approximating the time and cost of completing project deliverables." 

There are 2 types of estimates: top/down & bottom/up

1. Top/Down Estimates are estimates made by top management which will often come from previous experience in certain projects or are made when the team make a decision collectively. Top/Down estimates can involve understanding estimates by firstly identifying the final goal of the project, such as selling price and new upgrades that need to be implemented such as new technology updates on smartphones, creating a new smartphone which Samsung have done with the 'foldable' phone screen, building a new building such as the national children hospital  
2. Bottom/Down Estimates are done by the workers who will be doing the work in order to achieve the goals of top management. The estimates are based on costings of their time and effort which is based on the scope of the project. An example of bottom/up estimates are quotes of costings based on the quality of the work required, the time the work will take & the materials required to complete the work.

Estimates are required to create a efficient schedule of work for the project, to determine how long the project will take from beginning to end & to understand the total costs to identify if it will be within budget & cash flows, if the project is worth while, feasible and realistic and to monitor the project once it begin to takeoff. 

In order to ensure estimates are accurate, it may be suggested to initially have a meeting with top management to identify the project objectives and goals based on previous experience of the organisation or the previous professional experiences held by top management positions. Subsequent to meetings being held by top management and once final estimate objectives are made, to involve workers to allow clear and positive communication to have bottom/up estimates integrated into the plan by management. This clear communication and understanding of management goals allow workers who will be doing the work, creating the infrastructure or final product to determine if the goal of management is feasible and realistic. 

In order to receive the best bottom/up estimates, the project manager may find it useful and beneficial to get quotations from a number of contractors or people to understand if the time and costing estimates are correct - this will become apparent if the quotes are similar without any major differences. 

With estimates in place and approved by top management and project manager - a critical path can be illustrated in order to identify the best path to meet the objective utilising as little time as possible while adhering to the scope, activities and delivering the quality required. 

Estimates which are not accurate, realistic or constantly fluctuating, which can be seen in the time and cost estimates regarding the NCH. Bottom/Up estimates are given but are changing due to a T&C within the contracts that facilitates such changes within the estimates. These changes within estimates which have seen the project have cost increases from €450 million to €1.7 billion - the final cost is still unknown. Due to bad estimates at the beginning of the project, which have increased a shockingly amount - a project which is required to deliver medical care to children within the country and is supposed to be a positive for the country - is now a failure due to the terrible estimates given.

Estimates for a project, if they are top/down OR bottom/up should be as accurate as possible along with having some wiggle room for changes, if a bad estimate is given it can hinder a promising project.