The planning fallacy: why projects usually take longer than the estimate
Why you give a project too little time, even after being late before
Your last project ran late, and you know it. You plan the next one with care, and it runs late again. The trap is called the planning fallacy, and almost everyone falls into it.
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1
Miva runs a small bakery, and her phone rings all day with cake orders. You and Rono build apps for small shops, so she asks you for one, and how long it will take.
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2
You list the work, give each task a few days, and add them up: ten working days. "Two weeks," you tell her. That number is your estimate.
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3
It takes five weeks. Nothing terrible happened: the payment company had to check the bakery before it took card payments, the form broke on old phones, and Miva added new cakes. Each surprise cost a few days.
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4
The odd part is that you knew. Your last app, for a flower shop, also took twice as long as planned. But this time, the plan looked so clear.
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5
Guessing too little time for your own work, while you know that similar work ran late, has a name: the planning fallacy. The psychologists Daniel Kahneman and Amos Tversky named it in 1979.
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6
Miva loves her app, and she already wants a second one, for deliveries. You take a fresh sheet and start a new list.
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Go further
Two more names, if you want to look further.