The error in the number counts of LSB galaxies was determined by examining all the fields for high surface brightness galaxies.

Then (using NED), I determined both the all the galaxies that I should have found, as well as how many objects I had identified as galaxies which aren't (i.e. that are supernovas). These numbers provided my error for the count of LSB galaxies.

The NASA/IPAC Extragalactic Database.

references