A bit over two months ago I set out to find out what were the best and worst books in the EU. Not by one person's opinion, but the opinions of the masses to get a rough estimation of what the fans consider to be the best and worst books. In that quest I scoured five of the most popular websites that allow users to give ratings to books. These being Amazon, Barnes and Noble, Goodreads, LibraryThing, and anobii. I compiled all 1,522,923 user ratings on those sites of the over 280 EU novels into excel sheets so I can break down that data. Last month I compared the books to each other, ranking them and then breaking down the numbers further first looking at the adult novels, then the YA novels then all together. If you just want to see that or an explanation in how I got the numbers and the methods I used to calculate them you can do read it here.

Today I want to focus on how this data stacks up when applied to the series, and to rank the series. This will be the combined list of adult and Ya books but I have also done this for each of those individually.

But first I think it is important to state what I consider a series. Well I don't exactly have a hard definition for it but generally took every series of books that has an official or unofficial series name or grouping. Books that were released as part of a greater story like NJO, LOTF and FOTJ are of course counted, as are books that have a common thread such as the Callistia trilogy and Jax Pavan saga. I will also only be comparing these series with each other so all lists in this analysis will not include any books that are not a part of a series, either officially or not.

If you would like to see a more strict interpretation of series to include only those series that tell a larger story, and compare those to the standalones then I'll be happy to let you know I have done that and will be posting those results upon the conclusion of my analysis of the series.

Now if you've read my previous articles in this series where I explain the difference between the average and weighted average and what that means you can skip the next paragraph. But for those that don't I'll run through it again.

Lets say you have 10 books, each have a number of people that have given it a rating out of 5 stars, and an aggregated rating based on those ratings. How would you determine what the average rating of these books are? Well you could just take each book's aggregated rating and add them together then divide by 10. This would be the standard way of calculating averages and would give you a rating that was the average of the 10. However, what if those books don't have the same number of ratings? What if one or two books have well over twice the number of ratings as the others? Well to calculate the ratings by average wouldn't be fair, as more people have given those books the ratings they have than the others. So you could figure out the total number of stars each book got by multiplying the aggregated rating by the numbers of ratings. Then add each book's total number of stars together, and divide by the total number of people that gave a rating. This would give you a weighted average, and ensure that those books that more people gave a rating to are weighted more than those books that didn't. For the more mathematically inclined the formula looks like this.

I took the percent difference of every series on the list and ranked them to show which ones have the most variance between the books with more ratings than their peers, which resulted in this.

As you've probably become accustomed to if you have read the previous articles the books that are apart of series that weren't continuous stories are much higher on this list than those that aren't. Most likely due to them not being officially published as a series and being written by different authors.

So with all of that we have the list, or lists of all the series from worst to best, based on the metrics of over 1.5 million user ratings across the five major book rating websites. Again this isn't my opinion, this is just what the data says. So don't get mad at me if your favorite series isn't as high as you think they should be.

(Left Average, Right Weighed Average)

There is again a fairly consistent average between the two though it isn't as close as the adult novels. With the Average Star rating for the Average at 3.7703 and weighted average being 3.7769 There is again a bit of variation between these lists though the top and bottom are almost identical.

We'll also look again at the number of ratings each of these series got, and how many ratings per book in the series. This is more a pseudo measure of popularity as more ratings means more people have probably read it, but it is a bit imperfect for this as it is only showing how many people had a strong enough opinion to leave a user star rating. But the numbers are interesting nonetheless so I'll include them.

(Left Total ratings, Right Ratings per book)

I'll be back on Friday with a few other things I found in regards to the combined series that if I were to add here would make this article too long. In the meantime let us know what you think? How did your favorite series do? Which list do you prefer? Are there are any series that I left off or included that you don't think should be there? And if you have any other ideas on how to look at this data I've collected let us know.

This article is part of a series of articles, click here for the previous article in the series, and here for the next article in the series.

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