In most cases we see the natural CPC’s for mobile traffic starting off higher than desktop. And also for most of our clients the majority of their traffic is coming via mobile.

While we’re always pumped about more traffic, it’s more high-converting traffic that we really want. So looking at conversion rates and cost-per-lead metrics as main KPI’s in our accounts has lead us to using negative mobile bid modifiers for certain clients in certain campaigns.

For example, here’s the preliminary results from a recent experiment in mobile bid modification for a client in the service business—in elective medical. We’ve been working to lower their CPL below a $50 target for some time, and making steady progress.