Project estimating – optimistic planning bias strikes again

Do your projects suffer from over optimistic planning bias (OPB) – the tendency for people to be overly optimistic about the outcome of planned actions?

In yet another report by the National Audit Office the number of international passengers using the HS1 Channel Tunnel high-speed rail line is two-thirds lower than initially forecast, a report has found. It goes onto say:

“…the project went forward on the basis of hugely optimistic assumptions about international passenger numbers.”

Get your copy at

Get your copy at:








Turn to your projects:

  • is the delivery date over optimistic?
  • when estimating to deliver specific activities are you falling into the trap of being over optimistic
  • is your project sponsor (or senior management) suggesting delivery using optimistic planning bias – cost or time?

I ask these questions as I am finding more and more situations when either the project manager or team suffer from this ‘malaise’ or the sponsor or senior managers ‘impose’ a delivery date which means that the project should have started 3 months prior or they need more resources…which are not available!

I suggested to one course I ran that there is not sufficient knowledge of this issue. One person suggested that senior managers suffered from blindness – suggesting they do not want to know about the issue.

What are your thoughts?

One final point: the article mentions that the British tax payer made some money:

“…… it was sold for more than £2bn, far exceeding market expectations.”

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One Response to Project estimating – optimistic planning bias strikes again

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