Boston—Demonstrating mobile marketing's ROI is a top concern among companies planning to grow their marketing programs, according to a survey from Forrester Research and Aquent, a staffing company for the marketing industry. The study also found that few organizations have a full-time employee dedicated to mobile marketing initiatives. Forty-two percent of survey respondents indicated that measurement/ROI was their biggest mobile marketing challenge, followed by reaching the correct audience (34%) and data security (34%). Marketers also face staffing challenges when it comes to mobile, with 68% indicating they have to prove mobile marketing's positive ROI before they can hire more mobile marketing staff, the survey found. While mobile marketers need to understand mobile technology, they don't need to be programmers; those skills can come from IT, contract employees and agencies, the report said. But mobile marketers should understand marketing fundamentals, with 43% of respondents indicating their most successful internal mobile marketing staff members have a traditional brand marketing background. The survey of 155 senior-level employees with influence over mobile strategies was conducted online from August through November.