Already in 2014, marketers grappled with the rapid rise in mobile usage and the explosion of advertising data. In a mobile world, consumers are taking an increasingly complex buying path jumping from mobile to Web to in-store and back again -- interacting with social, display, and video campaigns along the way. Marketers struggled with how to allocate budget, how to gauge impact across channels, and how to accurately measure attribution.

Looking ahead to 2015, what concerns do marketers have? According to our new research that surveys 300 digital marketers in the U.S. and UK, cross-channel attribution will pose the biggest challenge in 2015. Some 58% of marketers said that difficulty measuring ad attribution will remain their most vexing issue. That’s not surprising, considering that more than 65% of revenue comes from purchases involving multiple touchpoints, according to Google. When a consumer clicks on a desktop search ad Tuesday, reads a few product reviews Wednesday, goes into a store on Thursday, and finally buys on her tablet on Friday, what is the value of that first desktop search? Clearly, marketers are still having trouble finding ways to crack the attribution conundrum.

What is marketers’ second-biggest concern? Digging out from under the data deluge. Half of marketers said the lack of visibility into advertising data would pose the biggest challenge -- and that’s no surprise, considering the amount of data that brands and agencies must now contend with. According to IDC, data in the “digital universe” is doubling in size every two years, and will multiply 10 times between 2013 and 2020 -- from 4.4 trillion gigabytes to 44 trillion gigabytes. This includes digitized data from social media platforms, mobile applications, geolocation technologies, and an ever-expanding number of media types. Marketers must now analyze petabytes of first- and third-party data to buy, target, and measure digital ads on every channel.

The third-most-cited challenge for 2015 concerns the ongoing divide between digital marketing teams. Some 44% of digital marketers say the siloed team structure between marketing groups -- social, mobile, SEM, SEO, display, earned, owned etc. -- causes complexity and inefficiencies. If all digital marketing teams could work more closely together to coordinate campaigns and measure cross-channel impact, campaigns would be more effective with far less wasted spend, marketers said. (Some 36% of marketers also said management in their companies doesn’t prioritize a cross-channel marketing strategy, and only 27% said their all their digital marketing disciplines were integrated.) Thankfully, as display and social become more programmatic like search, and as search begins to incorporate audience data from display and social channels, 2015 will be an excellent time to integrate marketing teams.

Overall, marketers believe that 2015 will be the year of the "audience" online. Precision targeting of specific ad creative to specific audiences will become the norm next year. Some 51% of marketers plan to create campaigns based on a deeper understanding of their core audiences in 2015, using first- and third-party data to accurately identify high-value audiences. Clearly, the majority of marketers know understand the importance of following the customers instead of counting clicks.

Not surprisingly, the problems marketers listed as their biggest challenges for 2015 align closely with their top priorities for the year:

1. Creating campaigns based on deeper understanding of audiences (51%)

2. Cross-channel digital marketing (50%)

3. Better integrating online and offline marketing efforts (46%)

4. Better integrating digital marketing disciplines (44%)

5. Investing in more sophisticated technology to gain and act on insights about

customers (33%)

2015 will be another year of big challenges -- but also big gains -- for digital marketers. One day, when machines and algorithms automate 100% of digital advertising, attributing every ad interaction with 100% accuracy, marketers will look back on 2015 as the dark ages. But, until then, marketers can take practical steps to break down silos, leverage data for deeper understanding of customers, and make inroads into correctly measuring attribution. If we only achieve those things in 2015, it will be a watershed year for digital advertising.