What Is Your Epsilon

Suppose the user's only interested in data that was taken at 10,000 feet. Well, the user doesn't really mean 10,000 feet. He means within some range around 10,000 feet. It's easy enough to force the user to actually turn this into a range. It could also be possible to guess a range and then narrow it if there are tons of hits or widen it if there are only a few.

But, on the other side of the coin. How accurate is the ALTITUDE keyword in your data? Do we need to index with error bars?

Some data may store ambient temperature in degrees Celsius. Other data may store ambient temperature in tenths of a degree Farenheit. Should we be keeping around a +/-.5C for the first one and a +/-.09C for the second one?

-- PatrickStein - 25 Mar 2005

There are a couple of ways to look at this. One is that our sensors will have IMU/GPS systems that enable the calculation of position values, possibly with some error estimate. In that case one can hope for values and bounds. Another view is that we will always be offered some data, that we want, for which we will be lucky to be able to attach nominal values for parameters. It would be nice to tag how the values we put in the data are come by. It is actually more than one, and probably many, different kinds of pedigrees.

-- HarveyRhody - 26 Mar 2005