No Fixed Rule
It is worth bearing in mind that although spending on different marketing media has changed fundamentally, advertisers are not so much choosing one medium over another as working out how each of us consumes and respond to different combinations of media. Some people first notice a product on social media, then research it further online, then buy it in store. Some are inspired by what is offered through direct mail and through e-commerce. Our research finds that stereotypical preconceptions are on the wane. Older people are doing as much online, if not more, as the young.