Extensive research has shown given that a current project is more than fifteen percent complete, the overrun at completion will not be less than the overrun incurred to date; and the percent overrun at completion will be greater than the percent overrun incurred to date. Assuming no change in scope or reduction in delivered capabilities, this overrun is locked.
Without knowing the original Estimate At Complete (EAC), the funders of the project have no way of making decisions about the project's total cost, its incremental cost, or how to adjust scope and duration to meet the expected cost incurred in exchange for the expected value produced from this cost. Without this cost information, and related schedule, and techncial performanc information, the notion of decision making is nonsense.
We can't make a decision without knowing the cost and benefits of the resulting decision
The absence of an estimated cost, duration, and delivered capability prevents the business from knowing if they are making the right decision about the investment in the project. So if decision-making is what management does, not knowing this information prevents credible decisions from being made
Not estimating these three data items – cost, schedule, and technical performance (delivered capabilities) – is simply bad business management. What ever unfavorable outcomes – overruns, failed business capabilities, unhappy customers (ACA the most recent example) – is well deserved.
The notion that we can make decision in the absence of estimates of their cost and benefit, appears to be unfounded conjecture, with no evidence of its validity.