You have a certain stable process that generates forecasts. You generate a forecast: 80% for A, 20% for B. B happens. You generate another forecast: 80% for C, 20% for D. D happens. You generate another forecast...
If events that you forecast at 20% keep happening and events you forecast at 80% keep not happening, how many forecasts do you need to recognize that your forecast-generating process is wrong?
Well, think about it this way.
You have a certain stable process that generates forecasts. You generate a forecast: 80% for A, 20% for B. B happens. You generate another forecast: 80% for C, 20% for D. D happens. You generate another forecast...
If events that you forecast at 20% keep happening and events you forecast at 80% keep not happening, how many forecasts do you need to recognize that your forecast-generating process is wrong?