Rating System

So, it might seem a little weird to have a page dedicated to how I rate music.  I mean, how complicated can it be, right?  And the truth is this isn’t really that complicated, but it’s complicated enough to warrant an explanation.

I use iTunes as media player and, as such, also use their standard 5-star rating system.  These are my personal ideas of what these five rankings mean:

  • 5-star:  I LOVE this song!  Can’t imagine living without it.
  • 4-star:  I LOVE this song too!….but not quite as much.  Can live without it…for a while.
  • 3-star:  I LIKE this song!  Can live without it, but would miss it.
  • 2-star:  I don’t like this song.  I’ll listen to it, but could easily live without it.
  • 1-star:  I HATE this song!  Turn it off….now!

This 5-star method is perfectly adequate for ranking songs.  Things get a bit trickier, however, when ranking albums (I’m old, I still call a collection of songs compiled onto a single release an “album”).  A popular method is to apply the same 5-star ranking to entire albums, but this is an injustice in my opinion.  Instead, I prefer to aggregate the individual song rankings to determine the album ranking.

The simplest means to do this would be to average the rankings of each song.   A ten-song album with five 4-star songs and five 3-star songs would have an album ranking of 3.5 stars:

  • Five songs * 5-stars = 25 points plus….
  • Five songs * 3-stars = 15 points equals….
  • 40 total points divided by 10 songs equals an average ranking of 4.

The problem with this is every song is given the same weight.  Imagine, though, if 8 of the songs were 5 minutes long, one was 10 mintues long and another 20 minutes long.  Imagine also that both the 10-minute and 20-minute songs ranked as 5-star songs.  We now have a 75-minute album that breaks down this way:

  • Five songs * five minutes * 3-stars
  • 3 songs * five minutes * 5 stars
  • 1 song * 10 minutes * 5 stars
  • 1 song * 20minutes * 5 stars

Adding the minutes of the album we get the following:

  • 25 minutes of 3-star songs
  • 45 minutes of 5-star songs

A 4.0 rating for this album would imply that half the album is of 3-star quality and half is 5-star quality when clearly that isn’t true.  I use a 3-step process to give a weighted average of the album’s individual song rankings:

  1. Determine the total number of possible “points” by multiplying the album’s total minutes by five (minutes * 5).  A perfect 70-minute album with all songs ranking 5-stars would have a score of 350 points.
  2. Determine the actual number of “points” by multiplying each song’s total minutes by its ranking and then summing them together (sum(song ranking * minutes))
  3. Divide the total actual points by total possible points

Let’s revisit our previous example and see how this approach changes the result:

  1. Determine total possible points:  70 minutes * 5 = 350 possible points
  2. Determine actual number of points:
    1. song 1:  (3 stars * 5 minutes)    = 15 points
    2. song 2:  (3 stars * 5 minutes)    = 15 points
    3. song 3:  (3 stars * 5 minutes)    = 15 points
    4. song 4:  (3 stars * 5 minutes)    = 15 points
    5. song 5:  (3 stars * 5 minutes)    = 15 points
    6. song 6:  (5 stars * 5 minutes)    = 25 points
    7. song 7:  (5 stars * 5 minutes)    = 25 points
    8. song 8:  (5 stars * 5 minutes)    = 25 points
    9. song 9:  (5 stars * 10 minutes) = 50 points
    10. song 10:  (5 stars * 20 minutes) = 100 points
  3. This yields a total of 300 points; dividing these actual points by the 350 possible points yields a rating of 85.7 or 86 (300/350=85.7).

So, taking the time of song into consideration the album’s score has changed from 80 to 87.  Not a huge difference but for someone like me, who cares about such things, this is important.

Hope that helps.




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