Understanding ROI: Are My Recruitment Metrics & Analytics Working?

There are countless job boards to advertise on and source from, niche job sites, diversity sites, social media groups, social aggregators that can pull contact information, and of course job aggregators that scrape sites and distribute jobs. Not to mention there are virtual career fairs, on-demand video interviewing, texting, and a wealth of other options for recruiters to source and connect with candidates. But with so many options and places to ñnd talent, how do you know where to focus your time? There are costs associated with many talent acquisition solutions, and they all take time to research and understand regardless of any additional costs.
So how can a recruiter or talent acquisition professional know they are spending their time on the sources that will provide the best ROI?