Our HR Director Rosie asked our Data Science Director Dick Fear to use data science to figure out when the best day in December is for Christmas shopping. Here’s what Dick had to say:

Working on Trendscope recently has taught me that clear and intuitive data science generally works best for client facing products. Therefore, in the spirit of simplification, this year I am retiring the Christmas Equation™ in favour of a simple data driven approach.

So let’s start with the question:

When is the best day in December to do your Christmas shopping?

There are a lot of possible answers, but I have real work to do so I’m going to keep it simple and suggest that the optimal day for Christmas shopping is simply the day when shops are least crowded and Christmas sales are most numerous. Conveniently, this definition also happens to be something I can measure using my old friend Google Trends.

For those who don’t know, Google Trends is a nifty tool for measuring the popularity over time of various search terms anywhere in the world. Therefore, if I assume that the popularity of the search term “Christmas offer” is highly correlated with the number of actual Christmas sales and offers (if you can’t make unfounded assumptions at Christmas, then when can you?) then the “Christmas offer” Google trend line should be informative:

Interesting! Looks like the best time for Christmas offers and Christmas sales is the second week of December every year from 2013 through to 2016.

But what about the crowdedness of the shops? For that lets try the search term “Christmas shopping”:

This time the yearly peak occurs during the fourth week of December, presumably because the shops get progressively more crowded right up to Christmas Eve, after which they drop off precipitously. That’s two weeks after the Christmas offer peak, which means that according to my definition of ‘best time for Christmas shopping”, the answer is the second week of December.

That was easy!

But, despite my penchant for sweeping assumptions and black boxes I am still a data scientist at heart, so lets do just a small amount of testing, since the search term “Christmas shopping” probably correlates with a whole load of things that may or may not include the number of people wondering around shops in London.

To test this let’s try the search terms “Westfield directions” and “Oxford Street”:

Would you look at that, they both spike in the fourth week of December! Therefore I conclude that the shops in London get progressively busier up until the fourth week of December but that Christmas offers and sales increase up until the second week, and then fall off. That confirms that the best week for Christmas shopping is the second week of December.

But what about the best day? Following the same logic as above there is a clear cyclical weekly pattern to searches for Westfield and Oxford Street which is highest over the weekend and lowest on a Wednesday or sometimes Tuesday.

Therefore, I can say with complete confidence that the best time for Christmas shopping this year is the 13th of December. And with that in mind, we’ll be shutting our offices at 3pm on the 13th December to make all our Swans have enough time to get their shopping done on the best day of the year!

Dick has been with Black Swan since day one. He founded our data science team, a group of labcoat-wearing doctors with diverse backgrounds in everything from astrophysics, to complex systems, to quantum computing. Collectively they know more algorithms than you can shake a stick at, and work as one to find innovative solutions to the toughest of business problems.