Ad spending as percentage of gdp has not changed in at least a century. So i m not sure if these new media are any more effective than any other media. I honest

Ad spending as percentage of gdp has not changed in at least a century. So i m not sure if these new media are any more effective than any other media. I honestly am baffled at the lack of scientific research of the effectiveness of advertising in the digital age, to the point of being suspicious. https://static.seekingalpha.com/uploads/2018/3/20/607954-15215770607489548.png https://static.seekingalpha.com/uploads/2018/3/20/607954-152...