Statistical anomaly regarding punctuality?

[christhebull]

I was at Clapham Junction and saw this display regarding train performance.

One doesn't have to be the best at mental maths to work out that the percentage of trains on time (90.4%), plus the trains cancelled (16.2%), is over 100% for the Overground.

Of course, I'm aware that Clapham Junction is always a terminating station for the Overground. Therefore a train could arrive on time and then have a departure cancelled due to driver shortages or other issues on the line. However this does appear to be a juxtaposition and I would be interested to know if any other stations have similarly improbable statistics where on time performance plus cancellations add up to more than 100%...

 

[CyrusWuff]

The two measures are independent of one another. Punctuality is (in this case) the percentage of actual station calls within three minutes of the scheduled time.

So if there were 1000 trains scheduled to call at Clapham Junction on a given day and 50 were cancelled, the Punctuality figures would be based on the 950 trains that did call there.