First off, not as many authors participated as I was hoping. I was hoping for a larger sample size, at least one-hundred authors. I got about 40. It's okay, but it's not great. Oh well. Perhaps if I were somebody like Konrath, I might have actually gotten a larger sample.
So, if you're not satisfied the results, and you didn't take the poll, then you have nobody to blame but yourself. :)
With such a small sample size, I feel the need to add some qualifiers before displaying all the colorful graphs. First off, links to the poll were posted in Reddit (r/writing, r/write, and r/selfpublish), Kindle Boards, and my personal Twitter and Facebook accounts.
Second, you'll notice that many of the people reported doing their free promotions Between December 16th - 31st, and February 1st - 15th. Considering the poll was made last Friday, February 24th, I suspect that many people who responded to the poll are either very experienced with Self Publishing and crawl these places for various information, or are newly self published and are crawling these places for information, and may not be as likely to return as time passes.
Third, I received a few comments that I should have added an "unsure" option to the yes/no questions, so some of the answers to the yes/no questions may be slightly inaccurate.
Fourth, I use Microsoft Excel only on occasion, so I know some of my graphs (particularly the scatter plots) are kind of funky. I apologize for this.
Now, let's move on to the meat of the poll: the results.
Once again, forty people responded to the poll. Between the forty respondents, there were 299,852 total free downloads reported, with an average of 7,496 downloads per person.
Let's take a look at the first question: "What was the start date of your earliest free promotion?"
The above data is pretty self-explanatory. As you can see, the more reported dates are the second half of December and first half of February. Obviously, due to the small sample size, the difference isn't really that significant, but it's definitely worth noting.
Now, let's touch briefly on the second question: "How many days did your free promotion last?" Spoiler alert: nobody does four-day promotions.
Again, the above data is pretty much self-explanatory: people love two day promotions, and four day promotions are pretty rare.
Now, for the real data, the whole reason I did this poll: "How many downloads did you receive on the first day?"
The reason I'm showing graphs for the number of downloads for the first day only is because, as shown above, everybody organizes their free promotions differently. Some people use one day at a time (like myself), while others use their five days all at once. It doesn't seem right to throw all that data into a single graph, especially when you think of cases where maybe one person got 700 downloads during a single-day promotion, while another got 1000 downloads over a five-day span. Logic dictates that the former author was more successful in their promotion, though the data would show the second person as being more successful.
Obviously too, you have strange outliers - like that person who had their book downloaded 21319 times on Day 1 (and 52438 times all together throughout a 3 Day Promotion). So, I redid this graph, but took out the four people who had 10,000+ downloads on their first day.
I have no idea if those "trend lines" actually tell us anything. I was hoping it would maybe show data for average number of downloads vs. time (and I was expecting this average to decrease with time, mostly due to the number of free books out there nowadays), but really, I think there's just too small of a sample size to begin hypothesizing such theories.
Also, these were the graphs I could not make to save my life, so I'll help you out: the data points appear in vertical columns, because I never asked people for exact promotion dates: merely ranges. The first vertical column is for people who did their promotions during the first half of December, the second for people in the second half of December, the third column for people who's promotions took place in the first half of January, etc.
Now, let's move on to the final three yes/no questions. I'll post all three at once, then discuss them at the end.
Agh, sorry that this last one appears larger than the others. Gross.
Personally, I actually found these yes/no questions to be the most interesting part of the entire poll. Why? Take a look: all three of these questions were answered with 80% Yes/20% No. 82% of people reported seeing a noticeable change in sales (we'll assume a positive change, since I saw no indication in the comments section that mentioned otherwise), 80% considered their promotions to be successful, and 80% plan to remain enrolled in KDP Select (of course, note that some people were unhappy with the lack of an "unsure" option, so it's difficult to say how these answers would differ had I had the foresight to put in that answer).
Quickly, I will note that CORRELATION DOES NOT EQUAL CAUSATION. Did you notice the scary bolded, italicized, and underlined text up above? In case you did not, let me say it again, though this time, in Large Rainbow Colors:
CORRELATION DOES NOT EQUAL CAUSATION.
In other words, we can't automatically assume that everybody who saw a change in sales saw their promotion as successful, and everybody who saw their promotion as a successful plans to enroll in KDP Select. One person may have seen the promotion as successful even with few sales, because he's just happy that people have access to his work. Another person may have seen their promotion as successful, but was only using KDP Select as a tool to get attention to their work immediately following release. Even though the end results all appear similar, we actually don't know whether that's just coincidental.
Also, allow me to pull a few responses from the "additional comments" section.
"I think the promotion was a success in that some sales came that may not have happened without it. But it was modest all the same. Regardless, I don't think it's a good idea to leave a book in KDP-S for more than one 90 day period. Using it for anything other than to launch a brand new book, before you place it on other channels, is just stupid, IMHO."
"It was interesting watching the numbers rise although mine never particularly took off on this first go at it. What was weird was that I had 6 sales 3 days after the promo but these came up as zero royalty so must have been late editions to the promo. I will remain in it and keep trying it as I have nothing to lose. I think the key is to get on something like Pixel of Ink."
"Better than I expected. Actually, fantastic."
"I like KDP select, but I've had enough requests from Nook readers to make me think it's a temporary thing for me."
"Very positive- I am enrolling all of my titles in KDP Select."
"January was a good month to go free, but... subsequent promotions have had dismal results with diminishing sales "after free" even though "freeloads" were fairly consistent (lower level than the first, but consistent)."
"All it did is get me one stars from people who complained about the theme of the book, which is stated quite well but since it was free they never bothered to check. Free does not work. Actually, it did do something. It made me raise my prices."
"Prior to Select, none of my books were selling well at all. I've now done this with four different titles with four different outcomes. The level of success varied wildly, but each time I was left better off than I was before."
"The problem with Select is that it follows the same model as regular book sales. Before, people were buying bestsellers. Now that they have Prime, they're borrowing bestsellers. Free promotions were more effective via Smashwords and Amazon's price-matching. I consider my experience with KDP Select a failure and I feel that an independent author needs books over many different distributors as opposed to one exclusive distributor that is offering no additional marketing or promotional value."
So, there you have it people. Mixed successes, wild variations in the number of downloads, etc. Feel free to add your own comments below, whether they're about your experience with KDP Select, your number of downloads, or your opinions on my sub-par polling skills. :)