How does your delay index differ from the information on the FAA airport delay map?

The FAA airport delay map shows the current status of air traffic control delays at US airports. It doesn't show any indications of cancellations or delays for reasons other than air traffic control directives. For example, on December 10, 2007, the FAA map showed "FAA on-time" for the Kansas City Airport (MCI) while we showed a delay index of 5 (as bad as it gets). In fact there were no air traffic control delays at MCI that day. However, nearly 15% of the flights at MCI were being cancelled due to really awful weather throughout the Midwest. This example shows the benefit of taking the approach of looking at the status of individual flights in aggregate to characterize airport conditions rather than the FAA's top down approach.