I posted the following graphs earlier but realized I hadn’t collected them here. I compared the number of ratings and reviews my nine books have received to the number of total downloads those books have received. Because most of my books are available exclusively on Amazon (in order to access the Kindle Unlimited program, which represents between 60%-80% of my revenue), it’s pretty easy to assemble sales and downloads numbers.

Here’s the strongest correlation I found. Roughly 1.7% of my book sales turn into reviews on Amazon, 1.1% of sales on Goodreads. Correlation is strong (R2 = 0.95). “Sales” include giveaway events (95% of my total downloads, because I do a lot of free promos). I left out my three-book box set, because its reviews often accrue to the individual books rather than the set.

Here’s a look at reviews and ratings compared to publication date. You might expect the books that have been out for longer to have more ratings and reviews, but that trend isn’t visible here. Therefore, I think it’s safe to say that marketing success is much more important to number of ratings/reviews than time since publication. The most effective marketing I’ve had is BookBub Featured Deals, and all the books that have the highest numbers of reviews/ratings have had featured deals except Flames Over Frosthelm (my book that’s been out the longest, and for which I’ve run the most non-BookBub free promos).

Here’s a comparison of written reviews vs. star ratings for all nine books on GoodReads and Amazon, sorted by total ratings. Written reviews are always fewer than ratings (that’s obvious – writing a review takes more effort than clicking a star), but the ratio doesn’t seem to be consistent over all my books.

You could potentially argue from this chart and its rough upward trend to the right that my less popular books have a higher percentage of written reviews. That may mean they’re getting those written reviews from fans or eager readers. The outlier to the upward trend is Flames Over Frosthelm, but that book has been out the longest, so it may just have had more time to accumulate written reviews. It also hasn’t had a BookBub featured deal, while the other three on the left have, and one interpretation of that is that BookBub readers are less likely to write reviews.