In studies of the effectiveness of some 12 campaigns, Nielsen says average incremental reach of adults 18-49 was boosted by 10.4% by adding online to TV.
In total, an average of 99 million 18-49 viewers were reached with the campaigns, with online adding an additional 10 million people.
Some 49% of the reach came from TV only; 7.7% from online-only, and 17.9% combined. Total TV reach, including some of the combined results, gave a TV a 67% reach; total online reach was 25.6%.
Nielsen says the 12 campaigns include advertisers in food, electronics, entertainment, financial and auto, which are looking to reach adults between 18-49 years old. The 12 campaigns -- served at least 1 billion television exposures and 100 million to 500 million online impressions -- reached almost 75% of the audience they sought, adults 18-49.
A recent Nielsen survey says that 62% of North Americans now use a second screen to browse the Internet while watching TV-video programming, and that 39% say they keep up with TV shows by using social media -- for everything from plot twists to product placements.