What Estimating Assumptions Can Hold Projects Back?

Question

What’s one assumption in estimating that you think the industry gets wrong?

Even small assumptions can have a big impact on cost, timelines, and overall project performance.

Any best approaches in how to overcome them? @AaronCohen @Aishwarya @AlexMacInnes @AndysGT350 @Ashish.Dhamal @Ben.Fochs @Bing Ma @Eddie.Fortier @Eric Ramirez @Garrett.Allred @Greggory.Joyce @Tim.Mowery @Guy.Lafond @Hbashiri @Jason Miller @JHANEY01 @Marshall.Luig

yuriwarwaruk · Answer

I'm curious to see how you @Greggory.Joyce @samehtalat have been able to harness AI to analyze historical data. Ideally we would be able to use data from In8 directly rather than dumping into Excel or other format that can be consumed by AI. I have been playing around with this a bit in Copilot but have not been able to do much with it so far.

samehtalat · Answer

@Greggory.Joyce @yuriwarwaruk

I agree with you, but in my experience productivity mainly affects the project’s direct cost — and this is an area where we can reduce uncertainty. With proper company benchmarking, productivity assumptions don’t have to be far from reality.Today, AI makes this even easier. Instead of relying on a dedicated team to extract lessons learned from completed projects, AI can quickly analyze historical data, identify actual productivity rates, and generate accurate benchmarks.Compared to the old days, when gathering this information was time‑consuming and inconsistent, we now have the tools to build much more reliable productivity assumptions and reduce the guesswork in estimating

Additionally, from my experience, one of the biggest incorrect assumptions in estimating is the way risk and contingency are allocated to the project budget. I often see that the risk register developed during the estimate phase lacks depth, mainly because the team doesn’t have enough experience identifying realistic risks or quantifying their potential impact.As a result, contingency is either underestimated or applied too generically, without truly reflecting the project’s uncertainties. This creates a false sense of confidence early on and leads to major gaps once execution begins

yuriwarwaruk · Answer

This is nothing new - in fact 1979 - This is not fiction

A 1979 study by the U.S. Army Corps of Engineers found that productivity declines with extended overtime

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