What is the correlation between births and toy sales? Are the number of births in a given year or years a leading indicator of toy sales three or four years later?
It would seem that there should be a way to forecast sales by the number of children available to consume toys. Yet, I have not seen an algorithm that proposes to forecast toy sales based on the historic relationship between birth and subsequent toy sales.
We cannot, however, overly simplify that relationship. A great movie or hot toy can, as it did in 2015 with Star Wars, dramatically effect the dollar value of toys sold to children. Also, competition from other forms of play and entertainment like a new video game console can also have an impact.
Yet, it would seem that the size of a child population has to be a major determiner of potential sales and that there would be a way to factor for variables like hot toys and competition. Minimally, it would seem that some bright graduate student looking for a dissertation topic might find a good topic in the relationship between the toy industry and annual birthrates.
If you know of a study please let us know. If you don't and know a bright student let them know.