rating question, help with a formula

Dolemite50

Hello,
I have a site that allows users to rate an item from 1-5.
My problem is, when I want to sort by rating, I dont want somebody that has a single vote of 5 to rank higher than somebody with 100 votes and a rating of 4. Can anybody please give me some suggestions or point me to a tute on this?

paulnaj

Hi Dolemite50,

You have to decide what the relationship is between rank and votes.

You know, how many votes are equivalent to one rank ... like 10 votes = 1 rank, say. Then, the 10*rank+votes will be the value that 'sorts' the list.

In general, if n votes = 1 rank, then the 'sort' value would be n*rank+votes.

Or you could just decide that rank always outweighs votes. Then you can just sort by rank, then by votes.

Hope that helps.

Paul.

Dolemite50

Thanks so much for the help.

The one thing that I'm not sure I made clear is that when they vote, its not a or b, its a rating from one to five. At this point I am thinking that the best way to go might just make all items "pending a rating" until they have 10 votes or so and then just sort them by AVG votes DESC COUNT votes DESC.

Any thoughts on this?

paulnaj

Hi again,

I thought that you meant that a voter could vote, whilst giving a rank from 1-5.

Then what could happen is, for example, 4 voters each give A a rank of 1, say and 1 voter could give B a rank of 5.

---+-------+------+
   | Votes | Rank |
---+-------+------+
 A |   4   |  4   |
---+-------+------+
 B |   1   |  5   |
---+-------+------+

Counting votes first makes A the 'winner', counting rank would make B the 'winner'.

Is this right?

Paul.

Dolemite50

Thanks for getting back to me. 🙂

In this scenario, people are uploading songs and other users have the ability to rate the song (once a day) on a scale from 1-5.
So if one member rates it a 2 and another rates it a 4, it now has an overall rating of 3.0. This works great but it seems unfair that if somebodys song has been rated 1000 times and has an overall rating of 4.75, it should be "ranked higher" than a new song that has one vote of 5 and therefore an overall rating of 5.0.

I'm thinking the pending rating option to wait until there are at least 10 votes in before it is rated may be the way to go.