Position matters when it comes to search ad clickthrough rates (CTRs)—especially for smartphones. Looking at Q2 2014 data from Marin Software, CTRs were better for first-position paid search ads run in the US on smartphones, tablets and desktops, with respective rates of 4.9%, 4.3% and 3.2%. And while this dropped with every level, the fall in CTRs on smartphones—30% per position, on average—was more dramatic than on tablets and PCs, down 28% and 22%, on average.
In all, first-position ads on smartphones grabbed nearly 40% of clickthroughs—more than double the 18% for second-position spots. Desktop search ads in the first position accounted for 30% of CTRs, while those on tablets claimed 36%. Though third-position ads grabbed a larger share of clickthroughs on smartphones than they did on desktops and tablets, this wasn’t the case for the remaining spots.
The layouts of smartphone and desktop search engine results pages (SERPs) are the reason for such differences, according to Marin, which pointed out that a smartphone SERP will often only show one ad at the top of the page, while the same results page on desktop will show three or more. Of course, advertisers should remember that CTRs aren’t enough for mobile ad measurement.
eMarketer expects 129.0 million US smartphone users to search via mobile browser or app on their phones this year, representing 78.0% of smartphone users and 40.7% of the population. By 2018, total smartphone searchers will reach 200.5 million—91.1% of smartphone users and 61.1% of the population.
As consumers turn to mobile devices for searching, advertisers are funneling more dollars toward the format. eMarketer estimates US advertisers will spend $8.72 billion on mobile search this year, an annual gain of 77.2% and a 38.1% share of total investments in digital search ads. Though growth will slow over our forecast period, increases will remain in the double digits through 2018, when mobile search ad spending in the US will total $25.69 billion, or 76.7% of all digital search ad expenditure.