The management of projects involves many things. Capabilities, Requirements, Development, Staffing, Budgeting, Procurement, Accounting, Testing, Security, Deployment, Maintenance, Training, Support, Sales and Marketing, and other development and operational processes. Each of these has interdependencies with other elements. Each operates in its own specific ways on the project. Almost all have behaviors described by probabilistic model driven by the underlying statistical processes.
Management in this sense is control in the presence of these probabilistic processes. And yes we can control these items - it's a well developed process, starting with Statistical Process Control, Monte Carlo Simulation of resulting, Bayesian Networks, Probabilistic Real Options and other methods based on probabilistic processes.
The notion that are not controllable is at its heart flawed and essentially misinformed. But this control requires information. It's been mentioned before about Closed Loop Control, Closed Loop versus Open Loop, Staying on Plan Means Closed Loop Control, Use and Misuse of Control Systems, and Why Project Management is a Control System.
All these lead to Five Immutable Principles of Project Success. Along with these Principles, comes Practices, and Processes. But it's the Principles we're after as a start.
Each of the Principles makes use of information used on managing the project. This information is the signal used by management to make decisions. These signals are used to compare the current of the project (the system under management) to the desired state of the system. This is the basis of the Control System used to manage the System Under Management.
With the control system - what ever that may be and there are many systems - the next step to gather the information needed to make decisions using this control system. This means information about the past, present, and future of the system under management. Past data - when recorded - is available from the database of what happened in the past. Present data should be readily available directly from the system. The future data presents a unique problem. Rarely is information about the future recorded some place. It's in the future and hasn't happened yet.
But we can find sources for this future information. We have models of what the system may do in the future. We may have similar systems from the past that can be used to create future data. But there is a critical issue here. The future may not be like the past. Or the future may be impacted in ways not found on similar projects.
But we to come up with this information if we are to make decisions about the future. So if we're missing the model, or missing the similar project, what can we do?
We can make estimates from the data or models in some probabilistically informed manner. This is the role of estimating. To inform our decision making processes in the presence of uncertainty of possible future outcomes, knowing something about the past and present state of the system under management.
With this probabilistic information, decisions can be made to take corrective actions to keep our project under control. That is moving in the direction we planned to move to reach the goal of the project. This goal is usually...
... provide needed capabilities to those paying for the project to meet some business goal or fulfill a mission strategy. To accomplish some beneficial outcome in exchange for the cost and time invested in development of the capabilities.
So what happens when we don't have information about the future. That is we choose to Not Estimate when faced with the uncertainty of the possible future states of the system we need to take corrective actions to keep the project moving in the desired direction?
Without these estimates, we have no signal needed to take corrective.
We have an Open Loop Control system. A system that takes any path it wants, it has no control mechanism to keep it on track.
The open loop control system is a non-feedback system in which the control input to the system is determined using only the current state of the system and a model of the system. There is no feedback to determine if the system is achieving the desired output based on the reference input or set point. The system does not observe itself to correct itself and, as such, is more prone to errors and cannot compensate for disturbances to the system.
This means we're going to get what we're going to get, with no chance to steer the system toward our desired outcome.
For any non-trivial system, not estimating the future state, creating the error signal between the desired future state and the current state and using that error signal to take corrective actions is considered Bad Management.
This would be considered
Doing Stupid Things On Purpose in most domains that spend other people's money to produce needed capabilities and the resulting value for the planned cost on the planned date.
