As you might have noticed — especially if you follow me on Twitter or on Google+ — for the last two days Till Undeath Do Us Part has been free to download on Kindle. At the moment that book — but not the other two — is signed up to Amazon’s Kindle Select programme, which lets me reduce the price of a book to zero for up to five days in every ninety, and gives a few other benefits — at the price of exclusivity. Currently Till Undeath is only available as an ebook for Kindle. (The others are still available as ebooks elsewhere.)

It’s an experiment. I generally favour making my books as widely available as possible, but a few fellow writers have experienced a decent and occasionally sustained bounce in overall sales after making one of their books free for a short time. I figured it was worth a try: evidence trumps dogma.

In advance I signed up to a few free services claiming they’d (try to) feature my book during its free period. I’m not sure if any did: I didn’t check.

I was tempted to give BookBub a go. On receipt of sufficient silver they will plug your book to some of their million-plus subscribers. Their Horror list has over 100,000 readers; at the time it would have cost me around $60 to include Till Undeath, with an estimated download count (from their tracking of previous such titles) in four digits. However, while my fingers hovered over the submission form, a line leapt out from their T&Cs: they don’t usually feature novellas. So I bailed out.

That’s the build-up.

On day one, Thursday, I posted to the usual places: here, Twitter, Google+, Goodreads, and even LinkedIn. I attempted to entice magazines such as Attitude, Gay Times, SFX and Starburst to retweet the offer (none did). I did receive a few retweets from friends and others, though: thanks to those who helped out. I tweeted in the UK morning, at lunchtime, and evening, trying not to over-spam.

On day two, Friday, I did virtually no promotion. The idea here was to see whether I could determine if tweeting etc had any measurable effect.

Anyway, here’s the chart you’ve skipped past the text to see.

Total: 433 downloads, dominated by 269 from the US and 127 from the UK. Then a surprising (to me) 21 from Germany, 9 from Canada, 5 from France and 2 from Italy.

Am I happy with these numbers? Yes and no.

I had no idea how many downloads there’d be. Not even an order of magnitude. 1? 10? 100? 1000? My cynical, self-deprecating self thought I’d be lucky to reach one hundred. My over-optimistic engineering-estimate self saw the numbers BookBub tossed around and wondered if I might hit one thousand.

I can’t say I’m unhappy with 433. That’s potentially 433 new readers, who might like the story and go on to buy my other books. It’s more copies of the book than I’ve sold. The goal was to increase visibility, and I’ve made some headway.

The shape of the chart — especially the Total curve — suggests day two’s lack of promotion didn’t make much if any difference. Downloads increased, slowing as you’d expect. If I’d kept the book free for a third day it might have exceeded 450 downloads but probably not 500.

In summary: a worthwhile experiment.

Now for the next stage: with prices back to normal, will there be a knock-on effect on sales?