Log actual vs. estimated time for every task

Build a personal database of your own estimation errors so you can calibrate future predictions.

Why it works

The planning fallacy persists partly because its errors are invisible: you finish late, update the calendar, and forget the original estimate. Tracking creates a feedback loop where the cost of optimism is made explicit and memorable. Calibration research shows that people can become better-calibrated forecasters through repeated feedback on their predictions — but the feedback must be systematic, not occasional. A running log of your own ratio (actual / estimated) is a personalized reference class.

How to do it

1. Before starting a task, write down your time estimate.
2. After finishing, record the actual time taken.
3. Calculate your personal ratio (actual / estimated) over a month of data.
4. Multiply your estimates by your average ratio going forward.
5. Review monthly to see if the ratio improves.

Evidence

Calibration training research (e.g., Lichtenstein & Fischhoff, 1980) shows that feedback on confidence intervals improves forecasting accuracy over time. Application to personal time estimation is mechanistically plausible but less formally studied. (mechanistic)

Most calibration training research is on probability judgments, not time estimates; transfer to scheduling is reasonable but not directly proved.

Sources

• Lichtenstein & Fischhoff (1980), Training for calibration, Organizational Behavior and Human Performance

Common mistake

Logging time only for tasks that went over estimate — this gives a biased sample. Logging only surprises skews your correction factor and makes you overcorrect.