Static Estimation Practices — The Experience Trap

NOTE: 4th post of a series on an HBR article by Prof. Kishore Sengupta, et al on The Experience Trap.

Re-planning the iron triangle — resources, time, and scope — is essential as a project progresses.  One of the more surprising mistakes experienced project managers make is to accept the original estimate as given.

In software development, initial estimates for a project shape the trajectory of decisions that a manager makes over its life….  The trouble is that initial estimates usually turn out to be wrong.

One of the most disappointing outcomes of this portion of the study is that project managers simply opted for conservative estimates, regardless of the evidence.  This behavior reinforces a negative stereotype about our profession, that we are risk-averse to the extreme. 

The idea was to give all subjects identical status reports, so we could compare how people’s productivity estimates evolved over time. Our hypothesis was that people’s productivity estimates would converge (people starting with low estimates would raise them over time and those with high estimates would lower them)….  So what happened? The managers’ productivity estimates did not converge over time. What’s more, there was a clear bias toward conservativeness: All their estimates drifted downward….  We suspect that this conservatism can be explained by managers’ attempts to game the system to get more resources.

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