Guys,
Based on this url i found Bayesian Rating, which explains the rating model very well, i wanted to summarize the formula to make it much easier for anyone implementing an SQL statement. Would this be correct if i summarized the formula like this?
avg_num_votes = Sum(votes)/Count(votes) * Count(votes)
avg_rating = sum(votes)/count(votes)
this_num_votes = count(votes)
this_rating = Positive_votes - Negative_votes
Gath
avg_num_votes = Sum(votes for all items)/Count(votes for all items)
avg_rating = Sum(Ratings for all items) / Count(items)
this_num_votes = Count(votes for THIS item)
this_rating = Positive_votes - Negative_votes --- For this item
It would look more like this:
avg_num_votes = Count(votes)/Count(items with at least 1 vote)
avg_rating = Sum(votes)/Count(items with at least 1 vote)
this_num_votes = Count(votes for this item)
this_rating = Sum(votes for this item)/Count(votes for this item)
If you are using a simple +/- system, Sum(votes) = Count(positive votes) (ie. treat + as 1, - as 0)
See also: Bayesian average.