The UK trade journal the Bookseller has once again shared the top ten ebook sales number as provided by Bookstat, and once again Hachette UK has shared its own sales numbers for its titles as reported by Bookstat.

Bookstat explains on its website:

To be useful, sales data has to reflect what your customers are actually buying. When you rely on data that misses 37% of the ebook and audio dollars they spend each day, or 60% of the books they purchase online, you’re flying your business half-blind.

Bookstat has not, that I’m aware of, made a specific claim on accuracy for its UK numbers, but for the US market Bookstat claims to track 96% of all online sales – ebooks, audiobooks and print.

But from the numbers The Bookseller shared with us from Bookstat, and from the numbers Hachette gave The Bookseller for four of the top ten titles, it’s clear Bookstat is missing 18% of Hachette’s ebooks sales.

Bookstat’s #1 top selling ebook is Hachette-published The Silent Patient. Bookstat says it sold 19,442 ebooks. Hachette says it sold 21,1660. Bookstat missed 2,218 sales.

Hachette title The Sister In Law sold 9,110 ebooks according to Bookstat. Hachette says it was 13,372, meaning Bookstat missed 4,262 sales.

Hachette title Where the Crawdads Sing sold 7,150 ebooks according to Bookstat. Hachette says it sold 8,002, meaning Bookstat missed 852 sales.

Hachette-published Little Whispers sold 5,890 ebooks according to Bookstat. Hachette says it was 415 more than that at 6,305.

In total Bookstat missed 7,747 Hachette ebook sales just from these four titles in the top ten. That’s 18% awry, and a long way from the 4% tolerance Bookstat claims to observe.

We have no meaningful way of knowing if the numbers for the other titles are any more accurate than those for Hachette.