It starts innocently enough. A new project is started – maybe it’s a digital transformation, a new product launch or a system overhaul. The team is energised, stakeholders are aligned, and there’s a sense of momentum in the air. The timelines feel tight, but doable. The budget is lean, but manageable.
And that’s where the trouble begins.
Welcome to the world of optimism bias – the silent saboteur of many projects. It doesn’t arrive loudly. It doesn’t look like hubris or recklessness. In fact, it often wears the disguise of confidence, enthusiasm and team spirit. But left unchecked, it’s one of the most consistent predictors of project failure.
What Is Optimism Bias?
At its core, optimism bias is the tendency to overestimate the likelihood of positive outcomes and underestimate the possibility of negative ones. It’s a human trait that appears in everything from planning a holiday to estimating the time it takes to clear out the loft.
But in project management, it becomes particularly dangerous because projects, especially complex ones, are inherently unpredictable. And when project managers plan as though everything will go according to the ideal path, they leave no room for the inevitable detours.
Why We Fall for It
The reasons are many. For one, most project managers want to reassure stakeholders, secure funding and move things forward. Under pressure to show feasibility and quick returns, it’s tempting to cut down estimates and to assume that what could go right will go right.
There’s also a cultural aspect. In many organisations, scepticism is mistaken for negativity. Project teams are encouraged to “think positively” or “make it work”. Those who raise red flags early in the planning stages are often seen as blockers, not realists.
Add to that a dose of overconfidence and it’s easy to see how inflated expectations can take root.
The Real-World Costs
Unfortunately, optimism bias doesn’t just affect timelines and budgets – it also undermines trust.
When a project begins to slip, what was once an inspiring plan can quickly feel like a broken promise. Leaders start questioning the team’s capabilities. Teams then scramble to play catch-up with the result that morale drops. In the worst cases, projects are scrapped, budgets balloon or reputations suffer – organisational and personal.
Consider how many large-scale initiatives – government infrastructure projects such as HS2 for one – have suffered because of underestimated complexity, ignored risks and overly optimistic forecasting.
The Good News
Optimism bias isn’t inevitable. It’s manageable if you’re willing to challenge it.
Start by grounding your project planning in historical data, where possible. What did similar projects actually take in terms of time, money and resources? Resist the temptation to say, “This time will be different,” unless you can prove why.
Be realistic and build contingency buffers into your schedule and budget. Anticipate delays, plan for scope changes and expect team turnover. You’ll rarely regret having done so.
Make risk conversations standard, not optional. Encourage your team to speak openly about potential obstacles. Turn devil’s advocacy into a formal role during planning sessions. In project management it’s better to confront uncomfortable truths early.
And most importantly, cultivate a culture of realism. As a project leader, your job isn’t to paint a perfect picture it’s to prepare your team for what’s likely, not just what’s possible.
A New Kind of Optimism
Ironically, the best way to be truly optimistic about your project’s success is to first strip away the false optimism.
By facing risks head-on, listening to dissenting voices, and anchoring expectations in reality, you give your project the greatest possible chance to succeed – not just in theory, but in practice.
Because true project success doesn’t come from believing things will go right. It comes from being ready when they don’t.
Very well explained.
Thank you – the problems with optimism bias in major projects is perhaps not discussed as much as it should be.