Book Selling Math for Book Bloggers

Of course there has been a hullaboo over whether book bloggers sell books. Today there was a post up at The Story Siren's which featured an anonymous author (Author X) answering questions about the correlation between book bloggers and book selling. So, I decided to do some math because hard numbers are better than anecodotal events where people remember one particular situation.

I'm going to have to make a whole bunch of educated assumptions for this exercise. If you think something is flagrantly wrong, please feel free to correct me.


Photo taken from ieslaroda-bilingue.wikispaces.com
Let's say 50 bloggers are sent copies of a book to review 25 get an ARC and 25 get a finished copy, and of the 50, 6 don't read the book and 10% of those who do read it don't like it. I'm going to assume that the publisher picked pretty well the people who would like the book and that the book is a good book since if a book is poorly written or is badly timed (say a vampire book right now when everyone is basically over vampires) then no amount of marketing is going to save it.

So based on these numbers lets do some costs:
$2 per finished copy in printing costs = $2 x 25 finished copy bloggers = $50
$3 per ARC copy in printing costs = $3 x 25 ARC bloggers = $75
Each book costs $2 to ship = $2 x 50 bloggers = $100
$40 for a person to take care of shipping stuff for half a day at $10/hour
Total Costs: $265

Ok, now for some more assumptions based on what Author X said in the Story Siren interview.
- 5 people will buy the book based on a blogger recommendation.
- I'm going to add to this that a number of people will become interested in the book say 30 (I'm going to refer to these as interests). A typical review may get say 150 unique views through all channels and a positive say generates interest in say 20% of the people who read it.
- Say the reviews that are bad generate a negative amount of interests say 15 per negative
- The blogs that don't review the book are likely to at least post that they received the book so they generate maybe 3 interest apiece

I'm going to assume that about 3/5 of the people that buy based on a single blogger recommendation get the hardcover ($15) and the other 2/5 get the mass market paperback ($8) since the promotion is likely happening around the time of the book's initial release. I'm going to say that more will buy at release or close to release rather than wait another year for the mass market.
Math:
40 * 5 = 200 books
120 of them are hardcover = 120 * $15 = $1800
80 of them are mass market = $640
Total Revenue: $2440


A note about interest, basically a lot of people look through a number of reviews, cover announcements, etc. before they actually buy a book. I'm using the term "interests" as a way to quantify this process.
Let's pretend that if a person gains 5 interests they buy the book at the same ratio of hardcover to mass market paperback. I'm going to say that 50% of the interests generated will go nowhere.
Math:
15*40 blogs who liked = 600
15 * 4 blogs who disliked = 60
3 * 6 blogs who merely mentioned the book = 18
Total: 1122 interests
922 * 50% = 561 interests
That translates to roughly 112 books sold in addition
67 hardcovers * $15 = $1005
45 hardcovers * $8 = $360
Total Revenue: $1365

I'm going to add one more layer of complexity from the people that read and like the book after buying it from seeing reviews and such. Basically I'm going to quantify a single step of word of mouth again by using interests.
Ok, so 312 books were sold. Let's say 70% of those people like the book so 218 people. Further, let's say each of them then generates on average 3 interests.
654 * 50% = 327 interests which amount to something.
That's another 65 books sold.
Say these are mostly mass market paperbacks 40 vs 25 Hardcovers
40 * $8 = $200
25 * $15 = $375
Total Revenue: $575

So that's 377 books sold for a revenue of $4380

Which means, for every $1 of marketing money spend there is $16.53 of revenue

I'm not sure whether this is a good amount or not as I have no idea of the industry standards on this.


Picture taken from Big Bold Business
But let's look at a signing:
Say it costs $350 in airfare to go to a signing (I know I'm low-balling this number) and hotel is $100 plus you have to feed the author $40 for the day. I don't think most bookstores charge to hold the event so no cost there.
Total Costs: $490

Say 70 people show up (this actually seems a bit high but I'm trying to give lots of leeway). I'm going to assume that all these people would have bought a book although only 15 (Edit: say 25) as a direct cause of the event and that all the ones bought are hardcovers. And perhaps another 10 buy a mass market paperback of an old book.
25 * $15 (Hardcovers) = $375 (edited for the 25 instead of 15)
10 * $8 = $80
Total Revenue: $455

ROI for a book signing: $1 of marketing dollar earns $0.93(edited for the 25 hardcovers instead of 15)

Obviously the marketing dollars don't match up quite as much, but there are ripple effects for an author that doesn't take the time to meet fans. Also, it's part of good relations with bookstores, so I will admit I'm not capturing all the future revenue from such an event. The speculation for those kinds of things though are far out of the realm of my experience so anything I would come with beyond the immediate effects of a signing would be pure BS.

Edit: The bottom line is that $1 per marketing spent on book blogs results in $16.53 in revenue for a publisher (based on my assumptions)