The free Amazon promotion for Helena Puumala's “Love and Rebirth on the Prairie” did all right, over the Valentine's Day weekend. It didn't get to number one in any category, like “A Christmas Miracle at the Lake” did, or like “The Summer Cottage Mystery” did. But it maintained a nice mid-teens showing in the category:
Literature and Fiction>Genre Fiction>Family Life
That must be a fairly popular category – it sounds like it ought to be anyway :).
"Love at the Lake" did OK too, considering that it wasn't its first spin around the block. It first came out last Valentine's Day, but its a good story and deserves a bit of push now and again.
It can be interesting observing the quirks of book sales and promotions. This one did very well in the U.S. Amazon store, but didn't particularly catch on in the U.K. store or the Canadian store. “A Christmas Miracle at the Lake” on the other hand, did very well in the U.K. over Christmas, but didn't break out to the same extent in the U.S.. “Summer Cottage Mystery” did surprisingly well in Japan, as well as the U.K and U.S..
Is it the cover that makes all the difference? Maybe the “Love and Rebirth” cover resonated best with North Americans, as it had quite a sweeping prairie panorama, a scene familiar to people in the U.S.. “A Christmas Miracle” featured a winter scene. Maybe the British romanticize wintry Christmas scenes more than Americans do. As for the Japanese response to “Summer Cottage”, maybe it was the cat on the cover. Japanese culture holds quite a soft spot for cats.
Maybe it is due to cultural factors. Perhaps Valentine's Day isn't as big a deal in the U.K as it is in the U.S., but Christmas is more important in the U.K. than the U.S., at least in terms of reading non-religious Christmas stories (not religious in the traditional church sanctioned sense, at any rate).
Of course, as a professional statistician, I have to keep in mind the vagaries of random chance – luck if you will. Sometimes a few people can start an information cascade, that then gains its own momentum, like a snowball heading downhill. Only God, and Amazon's data scientists know for sure, what really happens.
By the way, I did a little data analysis that showed that publishing short stories probably does have a fairly significant effect on sales of novels in the following month (assuming that we are holding the writer constant, in the experiment, and that the writing is of high enough quality). It seems to roughly double sales the next month. Unfortunately these are still “small n” statistics, so no guarantees. :).