Rating formula? Help apreciated!

Discussion in 'ASP .Net' started by alex, Mar 7, 2005.

  1. alex

    alex Guest

    I need a more advanced formula than just an average for calculating
    items rating.

    I have:

    raitng value is on scale 1 to 10.

    s - sum of all ratings for an item
    n - number of rates (votes)

    scenario 1)
    s=12
    n=2
    12/2 = 6

    scenario 2)
    s=24
    n=4
    24/4 = 6

    same average value, however what i would like to do is take into
    account number of votes for an item. item in scenario 2 should have
    higher rating that item 1, because it is more popular (viewed and rated
    more often).

    what kind of formula whould do this?

    thanks!
    alex, Mar 7, 2005
    #1
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  2. Hey Alex,
    I think there's two main approaches:
    1 - keep it as two separate values: Popularity and Rating. This is what
    CodeProject and MSDN both do. I think this makes sense because the two items
    tell very different things. One article with a 1000 0s should be rated lower
    than another article with 10 5s.

    2 - If you do need to combine them into a single value, then you need to
    scale popularity. For example, you may say:
    - Every 1000 hits = +1 Rating point. (i.e. s/n + n/k where k is your scalar).
    - make it non-linear = (s + n/k)/n.



    "alex" wrote:

    > I need a more advanced formula than just an average for calculating
    > items rating.
    >
    > I have:
    >
    > raitng value is on scale 1 to 10.
    >
    > s - sum of all ratings for an item
    > n - number of rates (votes)
    >
    > scenario 1)
    > s=12
    > n=2
    > 12/2 = 6
    >
    > scenario 2)
    > s=24
    > n=4
    > 24/4 = 6
    >
    > same average value, however what i would like to do is take into
    > account number of votes for an item. item in scenario 2 should have
    > higher rating that item 1, because it is more popular (viewed and rated
    > more often).
    >
    > what kind of formula whould do this?
    >
    > thanks!
    >
    >
    =?Utf-8?B?VGltIFN0YWxs?=, Mar 8, 2005
    #2
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  3. alex

    alex Guest

    Thanks Tim.

    This approach althoug makes total sense will add another variable in
    the formula.
    Why 1000? Why not 10? How do I decide?

    I just came across this:

    "ShutterPoint has adopted the individual numeric rating normalization
    method for calculation of the total rating for each photo. The method
    is based on the true Bayesian estimate formula, commonly used in
    statistics. The formula is:

    Total rating (TR) = (V/(V+M)) * R + (M/(V+M)) * C

    where:
    R = mathematical average for the photo (mean);
    V = number of received ratings for the photo;
    M = minimum number of ratings required for calculation (1);
    C = median of the rating scale (5.50)

    This method allows photos that receive higher number of individual
    numeric ratings to score a more representative total rating. Please
    note that individual numeric ratings are not shown."

    Looks liek there is a standart method in statistics for doing this type
    of things. Will test both methods and see which results makes more
    sence for my scenario.

    Regards,
    Alex







    Tim Stall wrote:
    > Hey Alex,
    > I think there's two main approaches:
    > 1 - keep it as two separate values: Popularity and Rating. This is

    what
    > CodeProject and MSDN both do. I think this makes sense because the

    two items
    > tell very different things. One article with a 1000 0s should be

    rated lower
    > than another article with 10 5s.
    >
    > 2 - If you do need to combine them into a single value, then you need

    to
    > scale popularity. For example, you may say:
    > - Every 1000 hits = +1 Rating point. (i.e. s/n + n/k where k is your

    scalar).
    > - make it non-linear = (s + n/k)/n.
    >
    >
    >
    > "alex" wrote:
    >
    > > I need a more advanced formula than just an average for calculating
    > > items rating.
    > >
    > > I have:
    > >
    > > raitng value is on scale 1 to 10.
    > >
    > > s - sum of all ratings for an item
    > > n - number of rates (votes)
    > >
    > > scenario 1)
    > > s=12
    > > n=2
    > > 12/2 = 6
    > >
    > > scenario 2)
    > > s=24
    > > n=4
    > > 24/4 = 6
    > >
    > > same average value, however what i would like to do is take into
    > > account number of votes for an item. item in scenario 2 should have
    > > higher rating that item 1, because it is more popular (viewed and

    rated
    > > more often).
    > >
    > > what kind of formula whould do this?
    > >
    > > thanks!
    > >
    > >
    alex, Mar 8, 2005
    #3
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