If you go on social media platforms like Twitter (a second home for many journalists), you’d be shocked to learn that Biden was the frontrunner in the polling so far. Fans of other candidates (especially Sanders) make their presence known quite loudly and can leave you left wondering if the polling is missing something.

My advice: Be very, very careful in looking at Twitter or other social media to understand who is ahead or behind in the Democratic race. The dividing lines in the Democratic primary are such that they expose social media’s weaknesses in accurately capturing the sentiment of the Democratic electorate.

Age is one of the biggest indicators in whom Democrats are choosing in the primary right now. Our CNN poll finds, for instance, that Sanders leads Biden by a 32% to 19% margin among those younger than 45. The same poll showed Biden with 36% and Sanders in third with 8% among those 45 years or older. (CNN’s Iowa poll revealed a similarly large age divide.)