Calculation for the reviews page

[KDLadage]

...hmmm another thought...

What about something like this:

(MEAN * MODE) / 3

Mean would have a mid-point of 3.

Mode would also have a mid-point of 3.

Thus, a product with a mean and mode of 3 each would have a rating of 3.00

However, the use of MODE in the equation would keep a single outlier from shifting the equation too much. In the case of a product with multiple modes, the average of the modes would be used...

 

[CRGreathouse]

Re: ...hmmm another thought...

What about something like this:

(MEAN * MODE) / 3

Mean would have a mid-point of 3.

Mode would also have a mid-point of 3.

Thus, a product with a mean and mode of 3 each would have a rating of 3.00

However, the use of MODE in the equation would keep a single outlier from shifting the equation too much. In the case of a product with multiple modes, the average of the modes would be used...

Why mode instead of median? Median tends to be much more meaningful... 5 votes for 3, 4 botes for 4, and 3 votes for 5 is closer to 4 (median) than 3 (mode).

Second, (Mean*Mode)/3 is less meaningful than Sqr(Mean*Mode), the geometric mean. In fact, Sqr(Mean*Median) is even more meaningful...

Still, none of this is likely to matter, because I doubt the exact scores were kept, in favor of a "running total" as Psi stated. Thus, median and mode are *gone*.

 

[KDLadage]

1. Median is more meaningful, and I think you are right about using the geometric SQR(MEAN*MEDIAN)
2. Since I can revise my vote, and it recalls what my old vote was, the information is still in the database...

 

[CRGreathouse]

Since I can revise my vote, and it recalls what my old vote was, the information is still in the database...

Cool. OK, then, if Morrus likes the system, it's all ready, as far as I can see.

 

[Morrus]

Cool. OK, then, if Morrus likes the system, it's all ready, as far as I can see.

I still don't understand it...

I get the mechanics of it - and could perform the calculation no problem. I don't get the logic behind using it, though (although I'm sure your logic is sound).

Can someone explain how it works, and its benefits, in layman's terms?

 

[praetorian]

I don't know exactly, but running it on a few items, the scores are fairly close to just the mean. I think the main purpose is to give the consistancy of the reveiws a slight importance. If you have a 3 given to a product with lots of 4s and 5s, or a product that gets a 4 while having mostly 2s and 3s, that extreme reveiw gets less influence, because while the mean dropped because of it, in most cases the median did not.

I have one really bad gripe though. The Forge of Fury as the tenth worst product, with a 3.78. Thats a very good rating considering the 10th best products are weighing in around 4.0. Is seven reveiws really the right number, especially for worst products? I mean, how many people are going to buy a product with a 2 rating and reveiw it, I doubt 7 people. I don't know, but 5 reviews seems a better number to me.

 

[CRGreathouse]

Can someone explain how it works, and its benefits, in layman's terms?

It decreases the effect of a single extreme vote, while still letting it count for something. Example:

Votes: 3, 3, 3, 4, 4, 4, 4, 4, 5, 5
Old method: 3.90
New method: 3.95

Votes: 1, 3, 3, 3, 4, 4, 4, 4, 4, 5, 5 (same, with an extra vote of 1)
Old method: 3.64
New method: 3.81

When the votes are close (as in the first example), the two methods have similar results, but when one stray vote is included, this proposed method minimizes its effect on the total score. This works both ways - a stray high vote is also minimized.

All of this is transparent to the user; the new method is still an average, though not a "typical" average. The results are i the same range as the original vote.