Originally Posted by

**TheAndruu** How can I determine the accuracy of some predictions? Take the example of weather forecasts. Each day weather.com has a predicted probability it will rain. Over a week then, we know the predicted

chance it would rain, and whether it rained on each day. How do I determine how accurate the predictions were over the past week?

For instance, for Sunday-Saturday of one week, here's the predictions and the actual results:

Day of week: Predicted Chance of Rain - Actual result (1 = it rained, 0 = it didn't rain)

S: .72 - 1

M: .31 - 0

T: .08 - 0

W: .01 - 0

T: .24 - 1

F: .51 - 1

S: .98 - 1

So given this, how do I determine the accuracy of the prediction percentages?