Our predictions fail in predictably bad ways. Picture the last time you were getting ready to leave the house and you were asked how much longer you would take. And when was the last time you actually left by then? You might be better at this than I am, but I have struggled with forecasting how long it will take. My dad used to account for this, and pretended we needed to leave 15 minutes before we actually did. Without knowing, my dad was accounting for Hofstadter's Law: