How to evaluate the influence of books in your topic area

When you spot a book online or in a bookstore, is it actually popular? That’s a much harder question to answer than you might imagine. And if the author is writing in your topic area, you need to know how much influence they have.

Here’s a list of ways that you can evaluate if a book is selling well.

How many copies did the publisher sell?

This, of course, would seem to be the simplest measure. But there are two problems with it.

First, publishers sell to bookstores. And bookstores return books. So even if a number appears on a publisher’s royalty statement to the author, that number may decrease if returns come flooding back in.

And second, publishers only share sales information with authors. So you have no way of knowing what those numbers are for anybody else’s book.

What is the sales number on Bookscan?

There is an industrywide book sales metric: NPD Bookscan. Bookscan accumulates point of sale numbers from bookstores, including physical stores and online stores like Amazon. It claims to track 85% of retail sales, but some credible people believe that it tracks a lower percentage. It doesn’t track ebooks, audiobooks, libraries, direct sales by publishers and authors, sales outside of traditional bookstores, or sales at independent bookstores that don’t participate.

Even so, Bookscan is roughly indicative of the popularity of a book. When an author pitches a publisher on a new book, the publisher likely uses Bookscan to assess how popular the author’s previous books have been.

The Publisher’s Weekly bestseller lists reflect Bookscan sales.

You can see your own Bookscan numbers on Amazon Author Central. But you cannot see anyone else’s books. Bookscan numbers for other books are only available to subscribers (which generally include publishers and some of the larger agents). So you can’t see numbers for other books.

If a book is selling well through other channels and generating influence, it’s likely to sell well within Bookscan-monitored channels, too. But there are a few exceptions — self-published books that sell by the thousands direct to consumers at huge author-run events, for example.

Did it appear on a bestseller list?

Many authors include the words “bestselling author” in their bios. It’s often not true, at least according to the way publishing industry professionals understand the words “bestseller.”

Having an orange ribbon on Amazon for a day or two indicates that you are a top seller in one subcategory. This can be fleeting, reflecting nothing more than a momentary surge in sales.

Other authors appear on the Porchlight Bestseller list, indicating a month of strong bulk sales. This often reflects sales at a few companies or speaking events, but not necessarily broader appeal.

The New York Times, The Wall Street Journal, and The Washington Post publish bestseller lists. Publishers will sometimes put a “badge” graphic on book covers to reflect the appearance of the book on one of these lists.

Appearing on these lists does indicate a high level of actual sales through the retailers that they monitor (although those lists of retailers are secret and proprietary). But there are flaws in these lists. For one, some authors manipulate their way onto the lists by paying tens of thousands of dollars for distributed bulk buying programs intended to make them appear as bestsellers, even though consumers are not buying the books. For another, the media organizations that maintain the lists will sometimes hide or reject books that they believe are attempting to manipulate their way onto the lists.

In general, authors that appear on one of these lists can call themselves bestselling authors. But you can’t be sure that their books are truly popular, and not just manipulating their way onto the list, unless they appear for several weeks at a time.

What’s the Amazon rank?

Every book on Amazon has a rank. For example, as I write this, James Clear’s Atomic Habits is ranked fourth among all books on Amazon. Bernie Sanders’ It’s OK To Be Angry About Capitalism is ranked number 91. The paperback version of Phil M. Jones’ Exactly What To Say is at 3,658.

To find the Amazon Rank, find the book on Amazon, click on the edition (hardback or paperback, not Kindle or audiobook), and the scroll down until you see the Product Details box, which looks like this:

While no one knows the exact algorithm for this ranking, the most credible estimate I’ve read is that it is an average of the ranking the book had yesterday and the rank among all books sold in the last hour. What is certain is that it is highly variable based on what’s happening right now. As such, it is likely to fluctuate from hour to hour and day to day.

A rank in the top 100 indicates enormous popularity. Anything in the top 1,000 is excellent. Anything within the top 10,000 is still quite good, especially for a book that’s been out for a while. Here’s one analysis of how rank relates to sales.

How many ratings and reviews does it have?

In contrast to sales rank, ratings accumulate and stick around. And ratings indicate, not sales, but people who were moved to go back and rate the book after (presumably) reading it. So a lot of reviews indicate that the book has influence, or at least had influence at some point.

A book with more than 100 Amazon reviews is making an impact. (Remember that only a small percentage of readers are moved to leave a review.) More than 1,000 is sign of major influence. Phil’s tally of 3,720 ratings in the graphic above reflects over a million sales.

In general, popular books will have not just a lot of reviews, but an average rating of 4.5 or more. Lower average ratings indicate a lot of haters who may not have even read the book. (People don’t generally buy and spread word of mouth for books they don’t like.)

Among my books, Groundswell had 162 ratings for the first edition and 139 for the updated edition; according to the publisher, sales were more than 150,000. Writing Without Bullshit had 208 ratings — it’s sales were lower, in the 20,000 to 30,000 range, but it’s a more recent book.

You can also check ratings on Goodreads. Writing Without Bullshit had 567 ratings there. Atomic Habits had 580,000.

If you want to know if a book didn’t have an influence, look for less than 20 ratings. Any published book with less than 20 ratings in the first three months made barely a ripple. (Check the publication date — if a book isn’t out yet, it won’t have any ratings yet.)

How many hits does it get on a Google search?

Search the title of the book (in quotes, no subtitle) and the name of the author (also in quotes).

A Google search for “Atomic Habits” “James Clear” has 2,750,000 hits — a major impact. Searching “Writing Without Bullshit” and “Josh Bernoff” gets you 4,390 results. “Transportation Transformation” by “Evangelos Simoudis,” a niche, self-published book I edited, has 3,100 results.

Any number in the tens of thousands here indicate a lot of people are talking about the book.
A number below 2,000 means there’s hardly any real impact.

What this all means

My regular readers will note the large number of weasel words in this post — words like “major impact.” That’s because there’s no definitive and quantitative measure of influence.

Here’s the bottom line:

If a book is on a major newspaper’s bestseller list for at least two weeks, it’s got a lot of influence. If it’s in your topic area, you have to address it.

If it has over 100 reviews on Amazon or Goodreads, it’s making an impact, and you may want to make friends with the author. (In general, authors in the same topic area can help each other.)

If, within 3 months after publication, it has not accumulated at least 20 reviews, it’s not doing well.

If you’re attempting to figure out if a book is making a difference to your readers — and if you need to address the topics in it in your own book — a combination of these measure will help you make that assessment. Every author deserves respect, but those making an impact are actually driving the conversation and changing how people think, and that’s what matters.