Confirmation bias is the tendency to seek and notice information supporting existing beliefs while avoiding or discounting contradictory evidence. In forecasting, it can make a favorable sales expectation seem better supported than it is. section 16.2.1
Watch for confirmation bias when:
- A team accepts one enthusiastic customer interview as evidence that a product launch will succeed. section 16.2.1
- A planner searches for evidence that next month will be strong while overlooking contradictory sales information. section 16.2.1
- Marketing stakeholders overstate campaign uplift because they want funding and work mainly with like-minded colleagues. section 16.2.1
- Forecast teams use one-sided data, demand selective justifications, or give disproportionate influence to particular stakeholders. section 16.4
A campaign forecast
A marketing team expects a campaign to increase sales and highlights favorable customer reactions while ignoring previous campaigns that performed poorly. A stronger process aligns incentives, considers a broad evidence base, gathers people with different perspectives, and lets contributors work independently before discussing assumptions. section 16.2.1 section 16.4
