After I started writing technical books I learned pretty quickly the power of Amazon. Not only has Amazon been one of the top online destinations to purchase books, but people know to go to Amazon to find book reviews. It is part of our Internet DNA.

I’ve heard from a couple of publishers that Amazon accounts for roughly 20-30% of their book sales, but I bet Amazon influences a much larger percentage because of the user-submitted book reviews. In fact, you can make a rough correlation between the number of Amazon reviews and the success of books. This also jived with what I saw with the top books in my category. The most successful books tend to have the most reviews.

Equating the number of Amazon reviews with increased sales, I wanted to devise a way to influence people to write reviews for my books. I thought of a pretty simple, but ultimately very effective way to do it.

I’ve authored several books that contain a lot of code samples (i.e., scripts). Each book might have 100-300 scripts. On my personal website, I created a page where anyone (even if they didn’t buy the book) could view each script. I gave the scripts away in order to drive traffic to my site hoping that people would want to buy the book.

It would be a pain to download 300 scripts individually, so I also provided a zip of all the scripts, but there was a catch. You had to send me an email and request it. This is where my Amazon engineering came into play. When I replied to the email (which I tried to do within a day), I attached the zip of the code and asked the person if they had any feedback about the book or wanted to see any additional topics covered in a future edition. If they replied and made some suggestions or gave feedback about the book, I sent them one final email asking if they minded providing a review of the book in Amazon (and I included a link directly to the book’s Amazon page). In some cases the initial email I received was very positive about the book, so I’d attached the code and asked for the Amazon review in my first reply.

In a two year period I received over 65 five-star reviews for the first book I tried this with (Active Directory Cookbook). This is unheard of for books in this category. You could add up the reviews for all other books with “Active Directory” in the title and it wouldn’t be as many as I received for this one book. I also believe this helped Active Directory Cookbook become the top selling book in the category for the last two years.

Not everyone that emailed me provided feedback about the book, so I never asked them to write a review. In the majority of cases, I replied with my standard email and the code and never heard back. I’d say this happened 90% of the time. With the other 10% where someone actually gave me feedback about the book, only about half submitted an Amazon review. Out of 1342 emails I received from people wanting the code, around 65 of them submitted Amazon reviews.

In October 2005, on the book’s two year anniversary, I decided to try another experiment. What if I gave the zip file away, directly off my website? Would the new reviews stop? At that point the book had 68 reviews, which was more than I had hoped for. I didn’t really need anymore. Five months later the answer is pretty clear. There hasn’t been a new review in Amazon since the day I stopped requiring people to send me an email for the zip file.

My Amazon engineering produced tangible results, but it is hard to say exactly what impact it had. Replying to over 1000 emails was no small amount of work, but I’m confident it helped contribute to the book’s success.