An apparatus comprising: a comparator to compare media presentation data representative of media output by a set top box to reference data associated with first reference media corresponding to a first station to determine whether the media presentation data corresponds to the reference data, the media presentation data collected while the set top box was tuned to a first channel number; a signature comparator to, when the media presentation data does not correspond to the reference data: identify a plurality of first signatures in a database that match a plurality of second signatures included in the media presentation data, the plurality of first signatures including at least one of first audio signatures or first video signatures, the plurality of second signatures including at least one of second audio signatures or second video signatures generated from the media output by the set top box; determine second reference media corresponding to the first signatures; determine that a second station was scheduled to present the second reference media at times at which the second signatures were generated; and associate the first channel number with the second station to create a second channel map to replace a first channel map that associates the first channel number with the first station based on channel lineup information for the set top box, the channel lineup information corresponding to a geographic area associated with the set top box; and a clickstream media crediter to correct clickstream data using the second channel map. a comparator to compare media presentation data representative of media output by a set top box to reference data associated with first reference media corresponding to a first station to determine whether the media presentation data corresponds to the reference data, the media presentation data collected while the set top box was tuned to a first channel number; a signature comparator to, when the media presentation data does not correspond to the reference data: identify a plurality of first signatures in a database that match a plurality of second signatures included in the media presentation data, the plurality of first signatures including at least one of first audio signatures or first video signatures, the plurality of second signatures including at least one of second audio signatures or second video signatures generated from the media output by the set top box; determine second reference media corresponding to the first signatures; determine that a second station was scheduled to present the second reference media at times at which the second signatures were generated; and associate the first channel number with the second station to create a second channel map to replace a first channel map that associates the first channel number with the first station based on channel lineup information for the set top box, the channel lineup information corresponding to a geographic area associated with the set top box; and identify a plurality of first signatures in a database that match a plurality of second signatures included in the media presentation data, the plurality of first signatures including at least one of first audio signatures or first video signatures, the plurality of second signatures including at least one of second audio signatures or second video signatures generated from the media output by the set top box; determine second reference media corresponding to the first signatures; determine that a second station was scheduled to present the second reference media at times at which the second signatures were generated; and associate the first channel number with the second station to create a second channel map to replace a first channel map that associates the first channel number with the first station based on channel lineup information for the set top box, the channel lineup information corresponding to a geographic area associated with the set top box; and a clickstream media crediter to correct clickstream data using the second channel map.