7. The method of claim 1 , wherein matching the first identification of closed captioning data received by the remote device and the second identification of closed captioning data stored in the database comprises: calculating a result of a hash function of the first identification of closed captioning data; and identifying, within the database, an entry identifying an item of content at an index corresponding to the calculated hash function result, the index equal to a result of a hash function of the second identification of closed captioning data.
1. A method for audience measurement, comprising: receiving, by an audience measurement engine executed by a processor of a first device, from a remote device, a first identification of closed captioning data received by the remote device during playback of an item of content; matching, by the audience measurement engine, the first identification of closed captioning data received by the remote device to a second identification of closed captioning data stored in a database in a storage device of the first device; retrieving, by the audience measurement engine, an identification of the item of content associated in the database with the second identification of closed captioning data, responsive to the match; associating, by the audience measurement engine, a device identifier of the remote device with the identified item of content; receiving, by the audience measurement engine from the remote device, a third identification of closed captioning data received by the remote device during playback of the item of content; matching, by the audience measurement engine, the third identification of closed captioning data received by the remote device to a fourth identification of closed captioning data stored in the database; retrieving, by the audience measurement engine, the identification of the item of content associated in the database with the fourth identification of closed captioning data, responsive to the match; determining, by the audience measurement engine, that the device identifier of the remote device is included in an audience list of the identified item of content; increasing, by the audience measurement engine, a value of a confidence metric associated with the device identifier of the remote device in the audience list of the identified item of content; and incrementing, by the audience measurement engine, an audience measurement counter for the item of content for each device identifier included in the audience list of the identified item of content having a confidence metric value greater than a threshold.