Calculate average rating

Question

Can any one tell me how to calculate rating average?

Is there any difference between rating average and ordinary average? — aioobe, Jan 21 '11 at 12:25
I really don't think that a programmer can ask such a question. It is like asking "How do I vote" as a president. — Pabuc, Jan 21 '11 at 12:39
http://www.evanmiller.org/how-not-to-sort-by-average-rating.html — Pranab, Oct 14 '16 at 08:06

aioobe · Answer 1 · 2015-02-24T12:58:05.003

13

I interpret rating average as the average of a set of ratings.

In that case you simply compute

                 sum_of_all_ratings
rating_average = ------------------
                  number_of_ratings

edited Feb 24 '15 at 12:58

answered Jan 21 '11 at 12:27

aioobe

413,195
112
811
826

Sekar, if this answered your question, I suggest you accept it so we get a closure on this. – aioobe Feb 24 '15 at 13:00

score 4 · Answer 2 · answered Jan 21 '11 at 12:37

I recommend this example :

Ordinary average : (a+b+c....z)/(number_added_items)

Rating average : (va*a + vb*b + vc*c... +vz*z)/(number_added_items)

In the first case you could say that the weight for each item is 1 as all items have the same weight in the calculation, while in the second case weights differ)

In your case the weight for each rating vote might depend on the voter so let's say a highly rated voter has a ponder for 3 his vote while a novice has 1.If 3 novices vote for an answer the rating of that answer will be (1*1+1*1+1*1)/(3) = 1 while if 2 high voters and a novice vote for an answer the average will be 3*1+3*1+1*1/3 = 2.33.

Does this answer your question? otherwise please be more explicit.

Thanks, catalin Marin!, i think the second case won't help me, b'coz i dont have different value for novoice & skilled one. so each have only one value pervote. so the first case suits me. Thanks once again... — vkGunasekaran, Jan 24 '11 at 12:40

Calculate average rating

2 Answers2