A before-and-after survey of Wednesday’s Democratic debate taken by FiveThirtyEight/Ipsos found that a panel of viewers said South Bend Mayor Pete Buttigieg and Massachusetts Sen. Elizabeth Warren had the best night. "Respondents, on average, thought Pete Buttigieg and Elizabeth Warren had the strongest debate performances, which is especially notable for Buttigieg because he was slightly less well-liked going into the night," wrote FiveThirtyEight. Minnesota Sen. Amy Klobuchar and New Jersey Sen. Cory Booker also scored high relative to their pre-debate favorability ratings, while Vice President Joe Biden and Tulsi Gabbard both had a rough night compared to their pre-debate favorability.
However, debate performances didn't proportionately transfer into whether certain candidates got a bump in how many people were considering voting for them. Biden, for instance, got a bigger bump than Warren, even though Warren and Buttigieg tied for best debate. Buttigieg, meanwhile, got a huge bump, which in some ways makes sense because he started out with considerably less support on the panel. Also, Vermont Sen. Bernie Sanders lost a tiny bit of traction, even though respondents said both he and Booker had the second-best night. Just a little context for viewing the chart below: