Wednesday, November 05, 2003

Anticipated xmlns Rating Range (0 - 100)

After considering many possible rating representations, I anticipate using the following numerical XML Namespace (xmlns) representation of ratings of resources (i.e. of songs).

Firstly, a five-star rating system with each star corresponding to the following rating descriptions will be used:

***** (5 stars) - Excellent
**** (4 stars) - Good
*** (3 stars) - Neutral
** (2 stars) - Poor
* (1 star) - Terrible

This system is symmetrical, with three-stars representing the central point of the range. This allows both positive and negative ratings to be made (as is the case at eBay where Positive, Neutral and Negative options are used). I have found examples where four-star systems are used, but five-stars seem to be more popular. Whilst I do not consider a Neutral, or Average, option being particularly useful to subsequent users as raters can select it and effectively opt out of expressing an opinion. However, it seems to be the generally accepted way to go so I think it is probably best to fall into line with it, as forcing an unfamiliar/undesirable system on users will adversely affect adoption.

Secondly, this five-star rating system will be represented by a numerical range of 1 - 100. So each star can be represented by a range of 20 as shown below:

***** (5 stars) range 81 - 100
**** (4 stars) range 61 - 80
*** (3 stars) range 41 - 60
** (2 stars) range 21 - 40
* (1 star) range 1 - 20

As most users will simply use a five-star rating front-end, without considering the detailed numerical representation behind each star, the middle of each range can be used as a default representation i.e.

***** (5 stars) = 90
**** (4 stars) = 70
*** (3 stars) = 50
** (2 stars) = 30
* (1 star) = 10

The twenty point ranges for each star will, however, enable raters to fine-tune their ratings should they wish to do so. I expect that this will be acceptably fine-grained for people who consider themselves to be expert raters to represent their ratings (e.g. a slightly better than Neutral rating could be 53, or a significantly better than Good rating could be 78 etc.). It also makes the rating representation compatible with iTunes from what I understand to be the case from Morbus Iff where a percentile representation is used behind the scenes, and other percentile rating systems such as Yahoo's LAUNCHcast.

Finally, an option of zero stars, and numerical representation of 0 (zero!), could be used for resources (i.e. songs) that have not yet been rated (i.e. are Unrated). This preserves the alphabetical ranking of rating descriptions (5 stars - Excellent, 4 stars - Good, 3 stars - Neutral, 2 stars - Poor, 1 star - Terrible, 0 stars - Unrated) and means the xmlns: rating representation would be a numerical range of 0 - 100.

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