How does Santa organise his lists?

D o you ever wonder how Santa knows how many Elsa dolls or Darth Vader figures to put in his sleigh before setting off on Christmas Eve? And, as Santa has billions of chimneys to go down, he needs to know where exactly to find the sack of presents for Donegal on his sleigh, or the sack of Chicago presents or the sack of Dublin presents. And there’s no point in having the sack of presents for children in Norway (which is near the North Pole) next to the sack for Australia (which isn’t!). He needs to have enough of each toy for every boy and girl, and his sleigh needs to be organised. And he doesn’t want poor Rudolph to pull a sleigh of toys that no one wants!

Santa uses statistics to help. Statistics is the science of data: the collection, analysis, interpretation and presentation of data.

So how does Santa collect data? Santa wouldn’t have time on Christmas Eve to record every single present he delivers (which would be called a census), so he only collects a sample, by recording the data from some of the letters he gets.

He then gets the elves to put the ‘data’ (eg names, ages, addresses, types of toys etc) into his huge computer. But he needs to be careful which letters he uses — if he used every letter from Australia and none from Canada, say, the data would tell him that all children wanted buckets and spades for Christmas (as it’s summer in Australia now), which mightn’t be a very nice surprise present for Canadian children at Christmas! So he needs to use a representative sample of letters.

Once in the computer Santa analyses and interprets the data in order to estimate or predict how many of each toy he’ll need next year. He can do simple things like count the number of Lego sets he delivered, but he can also find out much more exciting things from his data.

For instance, Santa and some of his elves can write a special computer code and add in more data from, say, the United Nations Population division to find out how many boys and girls of each age will be in each country next Christmas. He can therefore predict, on average, how many Lego sets he will need.

The science of statistics also allows Santa to estimate the smallest and largest numbers of Lego sets he is likely to need too, which is very useful. Santa’s final job as a statistician, is the presentation of data. He calls a meeting of all the elves, and uses graphs and plots and charts to show his predictions — how many of each toy they need to make, and which country’s sack to put them in, for example.

But, what about toys and books that only become popular during 2015? Santa has to update his data analysis and predictions as the year passes.

So, by the time all the children have sent off their letters to the North Pole, Santa’s elves have already been busy organising the toys and presents Santa has predicted he will need. All that’s left for Santa to do is to make his list and check it twice!