At Netroots Nation last week, I kept hearing the same two words come up over and over again. No, not “Bernie Sanders” — “Vanity metrics.”

As digital marketers, we have more access to more metrics than ever before. But it’s important to understand which numbers give us meaningful information about our programs — and which ones exist solely to make us feel good.

To understand the difference, it’s important to focus on program goals and sort data accordingly, rather than starting with all available data and attempting to gauge success based on metrics that may or may not be relevant. Sure, your post got a lot of shares from your dedicated supporters — but if your goal is to persuade an undecided audience, that may not be the most relevant piece of information.

Facebook recently took an important step in the direction of relevant metrics when the company announced earlier this month that it would redefine cost per click (CPC) to only include clicks to websites and apps — and not likes, shares and comments. Since almost all advertisers’ goal is an off-Facebook action, this change places the value on relevant metrics — and away from irrelevant ones.

On the other side of the coin, Derek Thompson’s February account in The Atlantic of his foray into Twitter metrics illustrates just how far down the vanity metrics rabbit hole one can fall. Despite the supposed popularity of Thompson’s tweets — based on metrics like impressions, retweets, shares and expands — just 1% of viewers actually accomplished Thompson’s desired action of clicking the link and reading his story.

And that’s just direct response — in the persuasion space, digital metrics can be even trickier. It’s tempting to believe that the persuasion ad with the most clicks is the most successful, even though data bear out no such correlation. After all, I could run an ad promising you a free iPad and the click through rate would be fantastic, but ultimately you wouldn’t be persuaded of anything (except that I am a jerk and you are probably not getting an iPad.)

I get it. It’s hard. For at least the past decade, we’ve all been bombarded with the message that the rise of digital media will bring a new age of total accountability and impeccable ROI, and sometimes that’s true. But sometimes you still have to do a phone poll.

Bottom line? Don’t be tempted by the siren song of vanity metrics. Evaluate data through the lens of your goals, rather than vice versa, and you can’t go wrong.