We are 93.5% accurate! But what does that mean?
Not so much actually.
Lengthy flight delays aren’t that common; only about 8% of flights worldwide have a delay greater than 60 minutes. So if we predicted that every flight will be on time or delayed less than 60 minutes, we would be correct 92% of the time! Sounds great, but not a very meaningful statistic.
Due to the dynamic nature of flight delays, our predictions for a given flight are intended to indicate a level of risk in the form “a delay of M minutes is p% likely,” as opposed to a binary prediction of “delayed” or “not delayed.”
Therefore we think about accuracy as the answer to the question, “Out of all the times we say a delay of M minutes will occur p% of the time, what percentage of the time does it actually occur?” If the answer is close to p then we consider ourselves to be accurate.
Here’s a look at our accuracy overall (based on a few major airlines, for flights during the most recent week as of the time of this writing):