More BookBub numbers

In the comments to the previous post on this topic, Johan P raised some really interesting points. I’d said rather glibly that the categories with more subscribers will obviously have more free-downloads and sales. As Johan points out this is counter-intuitive as the figures given are AVERAGES i.e. (I assume) the number of downloads/sales per book rather than the total number of downloads or sales in those categories. However, it really is true that the bigger categories have bigger downloads/sales but I haven’t explained it properly and I did use misleading terms like ‘crowded’.

The graph plots the totals of free-downloads + discounted book sales (horizontal axis) against number of subscribers. The relationship is quite strong. I plotted a line of best fit courtesy of Excel. Now a linear relationship is probably not the best way of describing the data. I assume that underneath all of this is some sort of power-law type thing going on with sales (i.e. some books sell HUGE amounts and shape the averages accordingly). How that all plays when comparing subscribers to sales would require more detailed data than we have. Even so, the line gives use something to compare the data we do have and an r-squared of 74% is enough to justify my claim that more subscribers=more downloads/sales as a broad statement.

Flipping this round, we get a different way of looking at the data: which genres deviate most from that line and in which direction? If I’m right and the sales figures are distorted by bestsellers, then a newbie author should stay clear from those genres ABOVE the line because these genres have more subscribers than we would predict from the number of downloads/sales. Genres below the line have more sales/downloads than we would predict from the number subscribers and that sounds like a better bet or at least those averages maybe closer to a ‘typical’ value rather than a distorted average.

Here’s a similar graph but this time looking at sales only and unfortunately done using Apple’s Numbers spreadsheet rather than Excel:

There are many ways we can quantify how much a data point deviates from that line but within the limits of the tools on this laptop, I’m just going to find the difference between the actual number of subscribers and the number predicted by the equation of the line. Negative is better here I think but I’ve sailed off into generating numbers whose meaning is unclear. I *think* that the genres near the top are less impacted by a few bestseller and the books near the bottom are more impacted but…I wouldn’t swear to that and I’m just guessing.

Women’s Fiction-1,166,549
Historical Romance-573,940
Christian Fiction-451,331
Erotic Romance-427,329
Romantic Suspense-418,864
Christian Nonfiction-397,638
True Crime-392,253
Paranormal Romance-391,022
Historical Fiction-372,395
Advice and How-To-358,251
Supernatural Suspense-347,481
Politics and Current Events-213,950
Dark Romance & Erotica-186,103
American Historical Romance-153,023
Time Travel Romance-62,258
Religion and Spirituality-55,485
Science Fiction-36,711
Chick Lit-6,255
Literary Fiction104,064
African American Interest104,971
Contemporary Romance115,599
Middle Grade122,818
New Adult Romance209,591
Cozy Mysteries309,753
Historical Mysteries317,139
General Nonfiction499,596
Psychological Thrillers600,214
Biographies and Memoirs631,754
Action and Adventure697,134
Teen and Young Adult968,973
Crime Fiction1,047,144

8 thoughts on “More BookBub numbers

  1. This is really funny.

    Bestsellers mean a genre is hotter because bestsellers bring in loads of new readers, a large percentage of who then browse outward in the genre and sometimes beyond the genre. It’s the symbiosis factor of fiction that popularizes genres in cyclical time periods. So the larger the number of bestsellers, the more the sweet spot the genre is and the more books can be funded in that genre by sales and license deals, making it bigger, which then draws in more readers who browse. You can’t find which genre is the biggest in the overall market if you discard bestsellers.

    So at best you’re just measuring the eco-system at BookBub, not the overall fiction market itself, with an eye to just finding the sweet spot for BookBub subscribers. In that case, you can try to remove the skewing bestsellers to see which genres get the most attention overall in numbers of titles through downloads and sales from BookBub subscribers as a select audience.

    But. BookBub is a free, curated email list that “searches” books for subscribers. They make their money by getting authors and publishers to pay them to list their books to subscribers. I.e. it’s not a curated list selected by experts as BookBub claims — it’s who pays gets the promotion. That means that the subscribers’ choices are shaped by what they get to chose, which is those authors/titles from publishers who think BookBub subscribers will be interested and who have the money to pay for BookBub’s promotion fees. That means the author/publishers’ biases about what the sweet spot genres are — and thus worth advertising through BookBub — shape the list of what is available in each genre. And that affects the subscribers’ behavior, as the titles they might want to most download aren’t necessarily available through BookBub because those author/publishers don’t pay BookBub to promote. Consequently, a genre that has more paid promotions of leading authors, like say romance, will attract more subscribers than one that does not.

    Complicating your analysis are the average reading habits of core fan readers of different genres. Romance fans read a large number of books, because romances are on average not super long works, are produced in great quantities and often at a high rate of productivity — it’s what they are used to. So BookBub’s subscription base may have a smaller number of subscribers for romance generating large downloads/sales. Whereas core readers of horror have not had as consistent a category dedicated market and tend to be a really large group of readers who read a select number of horror titles by particular authors and so are likely to be a large group of subscribers who generate smaller downloads/sales per subscriber.

    And then there is the simple fact that these categories are first off endlessly cris-crossing each other and second seem to include several categories that aren’t really a thing in book-selling and are instead particular to BookBub’s list. American Historical Romance for instance is not a thing — it’s part of historical romance and Regency romance. Chick Lit is part of Women’s fiction and has often been used as a synonym for women’s fiction and a lot of women’s fiction is historical fiction. Action and Adventure are thrillers, etc. So you’re getting groups of subscribers operating under BookBub’s system with BookBub shaping the genres that exist for them. So again your data is specific to BookBub’s subscribers and what they are being sold, which is shaped less by bestsellers skewing data than by what authors/publishers think BookBub is worth it as a promotional service.

    And then there is the issue of name recognition which is different from but related to sales. The point of giving away a book to thousands or millions for free is to hopefully build word of mouth for later paid sales but also to spread greater name recognition that the author exists — which will then hopefully lead to later paid sales. It’s a form of advertising that may have limited effects for fiction (much more for non-fiction,) but might still be very useful for some authors to simply have people familiar with their name, especially self-publishing authors trying to get people familiar with their name out of millions of other self-publishing authors. So some authors may be willing to pay BookBub to list their title/name to subscribers even if this does not result in a lot of downloads and sales simply as a big billboard ad. In that case, for many authors, the number of subscribers for the genre may be the sweet spot and the number of downloads and sales for that subscriber group irrelevant. They just want the subscribers to have seen their name and then possibly remember it when talking to others or if they see it again for a title being sold later on, to have the name be familiar, thus indicating to those who remember seeing it and those they talk to about it that the author is more popular/known than the author actually is — and thus maybe worth checking out. So some authors are only interested in promotion on the one axis.

    Liked by 1 person

    1. //Bestsellers mean a genre is hotter because bestsellers bring in loads of new readers, a large percentage of who then browse outward in the genre and sometimes beyond the genre.//

      Good point!


    2. It’s true that BookBub does show a curated selection of book deals to its customers, based on who is willing to pay for their services (ad the fees are very high, particularly for popular genres). Nonetheless, BookBub still gets way more submissions than they have free slots, so they can be choosy and pick the books they believe their readers will be interested in. It’s a bit of a mystery just what criteria they apply. But there are indie authors who repeatedly get BookBub ads, often for the same book, and others who keep submitting without any luck. And yes, scoring a BookBub ad is still considered the holy grail for many indie authors.

      As for their genre lists, I was tempted to say that BookBub uses Amazon’s categories, which are not necessarily identical with BISAC categories, but Amazon doesn’t have a chick lit or American historical romance category either, though they do have western romance, which can be historical as well as contemporary. I suspect that the BookBub people realised that chick lit and women’s fiction attract different audiences. Ditto for general historical romances and American/western historical romances.


      1. It looks like you can buy an ad, which is very expensive, or try to get listed, which is also expensive but less so. There are millions of self-publishers so yeah, they can’t sell to everybody, but it’s still a list that is shaped by authors’ ability to pay the fees and by those authors who chose it as a viable promotion option. So bestsellerdom isn’t the driving force — BookBub isn’t trying to do things that are necessarily popular and thus of most interest to the maximum subscribers. The interests of the people running BookBub shape what is available to subscribers, which in turn affects subscribers’ behavior.

        Chick lit is women’s fiction, a very broad category that simply means stories about women written usually by women authors, and when the chick lit label got popular, chick lit was used to refer to all women’s fiction, historical and contemporary (but not specifically romance.) Chick lit as a sub-genre is basically women’s fiction that has humorous aspects and is usually contemporary, but many such books may also get called women’s fiction and not chick lit. So they aren’t two different categories with two different audiences. But by having it pretend to be two categories, BookBub can sell more list placements. 🙂 Same with the nebulous use of “crime fiction” which could be nearly anything in suspense and is a synonym for suspense fiction.

        In the book-selling market, historical romances set in the American Old West are not really sold separately from the big category of historical romances. Regency romances, however, are a separate sub-category from the rest of historical romance because of the tradition going back to the 1930’s. Western romance (sometimes called Americana romance) in a contemporary setting is a very popular sub-genre of category romance. Apart from romance, westerns as a genre can include stories that have highly romantic sub-plots but not central romances and while westerns used to have their own category market, it wasn’t sustainable so now they’re sold in general fiction as a sub-set of historical fiction. It makes sense to have a westerns category, maybe, but having an American Historical Romance category (which may or may not be limited to Old West settings,) seems very odd as it has no established base. I don’t know if BookBub did a marketing survey that found they had subscribers who wanted that specifically or somebody running the place just likes that topic.

        So they just have their own weird little system. And there’s nothing wrong with doing that, but it does sort of skew CF’s result attempts since they don’t correspond to the categories and sub-categories used in the book-selling market that readers are more used to. Numerous titles could be listed in multiple categories at BookBub and I’m sure sometimes they do that for set fees for it. But if they do that, then comparing the genres to each other when they may have more than one listing gets rather tricky.

        Liked by 1 person

  2. There’s some distinct heteroscedasticity going on there, so yeah, I wouldn’t lean too hard on that linear regression. You could try a log transform of the data.

    Liked by 3 people

  3. I noticed that has a few captures of the BookBub page going back to late 2013:*/

    I only compared a handful of genres/rows on a single page chosen at random from March 2016 against the current data, but it seemed:

    * Subscribers had gone up slightly – maybe 10-20%? – but I would image a fair amount of older subscribers are dead email accounts, so maybe not that much of a change in reality?
    * Fees had gone up quite a bit – not quite doubling in price, but not far off
    * Average free downloads were roughly the same – some slightly higher, some slightly lower
    * Discounted sales dropped quite a lot – 25% to 30% on the ones I examined

    No idea what – if anything – this might indicate, but I assume that this has been noted, discussed and analysed in marketing forums on indie author/selfpub sites?

    Liked by 2 people

    1. BookBub and its effectiveness are discussed a lot on forums aimed at self-publishers. The consensus seems to be that even though BookBub is a lot more expensive and no longer quite as effective as it once was, largely due to Amazon algorithm changes, it’s still considered a good investment for many.


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