Monday, December 10, 2007

Assessing the Development of a Station: ASUD

Nowadays, the inputs that are used by a player for a particular station are almost entirely public. As long as, the person who created the station has not set their profile to private, you can read the lists of artists, song seeds, thumbed up tracks and thumbed down tracks.

Back in the early days, a few of us gathered at (now defunct and cybersquated). We came up with the idea of measuring the development of a station as a list of the number of Artist seeds, Song seeds, Ups and Downs (ASUD). Tim, IIRC, when he created the first version of proposed a measure D which was equal to the sum of the numbers of Ups and Downs, but the rest of us had already grown used to ASUD. And I think it's still a useful place to start.

Artists It's good to keep the number of artists in the station separate from the other numbers because the number of tracks called upon by an artist seed is the one thing about a station which can change without the user's input. Pandora analyzes and makes available for play new tracks by an artist on an on-going basis. The number of tracks available for popular artist who is still recording will always tend to increase over time. The number is more static for more obscure artists. (Interestingly, the founder of Pandora, Tim Westergren, was in the band YellowWood Junction which has exactly three songs available for play and that number has not changed in the past year at least.)

Songs Each song which is added to the list of song seeds for a station becomes available to form the basis for a set of four songs to play on the player. As similar songs are added to the list the station generally becomes more and more focused. Thus, because the number of tracks represented by an artist seed is fairly random, dynamic and difficult to assess, the number of songs seeds is probably the second most important measure of a station's development (after the number of thumbs down).

Ups The entire list of thumbed up songs serves as a single possible basis for a set. I used to believe that all the thumbed up tracks could individually form the basis for a set, but the Pandora FAQ now definitively states that that is not the case. Thus, the number of Ups gives a good idea of how much the creator has listened to a station, but it's the least important measure of the development of a station.

Downs On the other hand, the number of thumbed down tracks is an absolutely crucial indication of how well developed a station is. No thumbed down track will ever play on the station again, and, as long as no track by an artist appears in any of the other three lists (artist seeds, song seeds, or thumbed up tracks), two Downs ban all the tracks by that artist from the station. Thus, unless you are consciously moving tracks into the list of song seeds, cutting out songs one by one via the thumbs-down is the most usual way to incrementally improve a station.

The best measure of a station's development would be a count of all the songs which can be the basis for a set and a count of all the tracks that cannot play on that station. Unfortunately, those two numbers are difficult to calculate and until they become readily available ASUD is the best surrogate we have.