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I just received a 5-star review on a book that now has 7 reviews. That review boosted the average review rating from 4.5 to 4.6. An improvement of 0.1 points.

Great!

But then, I do a bit of arithmetic and see that if I next get a 1-star review, it will reduce my average rating to 4.0 - a huge reduction of 0.6 points. If that happens, it would be the impact of just 2 reviews - one totally positive, one totally negative. But it seems to me that the totally negative impact is way greater than the totally positive impact,

Seems unbalanced. Or is it? I dunno. Could be a bit of mathematically - challenged stuff going on on my part and I probably shouldn't even be thinking about it. But for those of us with limited numbers of reviews, it matters in terms of being accepted, or not, by some of the better promotional sites.

Whatdya all think?
 

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Math teacher here!  It's because of the reviews you already have. If your average is already high than another high review won't change it much. But a low review will have an impact. It works in reverse too. If you have say an average of 2 stars and you get a 1 star, it won't make that much difference but if you get a 5 star it will have a larger impact. It also depends on how many reviews you have too. The more you have the less impact a single rating will have on the overall average.
 

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Philip, the problem with your theory is that you're assuming the average book starts at 4.0.

Let's assume a book with no reviews starts at 3.0. Then a 5 or a 3 is a difference of 2 either way. From 3.0 you have to earn your way up or drop depending on the quality of the book.
 

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Philip,
Quick how to average.
(5a+4b+3c+2d+1e)/(a+b+c+d+e)
The letters are the number of reviews.
Editing to show real math.  I am using Havana 62
you have 2 5 stars 7 4 stars 2 3 stars and 1 each 1 and 2 stars. So here goes
(5 (2)+4 (7)+3 (2)+2 (1)+1 (1)/(2+7+2+1+1)
(10+28+6+2+1)/13
47/13
3.61
So you have an average of 3.61 stars which rounds up to 4 on the page.
if you get depressed go look at E L James.
 

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cinisajoy said:
Philip,
Quick how to average.
(5a+4b+3c+2d+1e)/(a+b+c+d+e)
The letters are the number of reviews.
Editing to show real math. I am using Havana 62
you have 2 5 stars 7 4 stars 2 3 stars and 1 each 1 and 2 stars. So here goes
(5 (2)+4 (7)+3 (2)+2 (1)+1 (1)/(2+7+2+1+1)
(10+28+6+2+1)/13
47/13
3.61
So you have an average of 3.61 stars which rounds up to 4 on the page.
if you get depressed go look at E L James.
HA! Cinasajoy, your just trying to reach Isaac Asimov level with 10k posts aren't you? No one likes math enough to do what you did! ;)

Hehe, I actually did well in math right up till the time that it started adding letters into the math problems and the letters didn't spell any words I knew :eek:
 
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THIS: Math teacher here!  It's because of the reviews you already have.

I'll add in one thought.

What's the average book rating?

If the average book rating is 3 stars, then a system that weighs 5 stars and 1 star equally is fine.

However, if the average book rating is more like 3.5 stars, then a system that allows 1 star ratings gives negative reviewers a lot of power. Just a couple of 1 star reviews can drag down a book's rating.

Oh, one more thing.

If you're aiming for 4 stars or above.

You require 4 5-star reviews to balance out a single 1-star review.

In that case 1 star reviews become too powerful.
 

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ireaderreview said:
THIS: Math teacher here! It's because of the reviews you already have.

I'll add in one thought.

What's the average book rating?

If the average book rating is 3 stars, then a system that weighs 5 stars and 1 star equally is fine.

However, if the average book rating is more like 3.5 stars, then a system that allows 1 star ratings gives negative reviewers a lot of power. Just a couple of 1 star reviews can drag down a book's rating.

Oh, one more thing.

If you're aiming for 4 stars or above.

You require 4 5-star reviews to balance out a single 1-star review.

In that case 1 star reviews become too powerful.
Or, to turn this upside down, 5 star reviews become too powerful: if a book is really really bad, one gushing, possibly fake, 5 star review can make it look better than it really is.

Which is why discerning readers are smart enough to look at the overall spread and sample some of the best and worst reviews to figure out if they can be taken at face value.
 
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