Anthony Sledge, a growth marketing manager at Lyft, had a sneaking suspicion that most riders want to tip their drivers, but just forget. In fact, he was one of them. “I tip on everything—food delivery, coffee, everything.” But not rideshare. “I wanted to see if I could make it even easier for people like me to tip.” Sledge works on the Marketplace team, which focuses on helping drivers understand the best ways to earn on Lyft, either through driver incentives or making the most of their time on the road. In his mind, making it easier for riders to give tips was yet another opportunity to increase driver earnings.

To get started, Sledge set about putting some hypotheses together. His first test was to use feel-good sentiment, sending holiday-themed push notifications to two million riders who never or rarely tip their drivers, 15 minutes after their rides ended. One control group received no push notification, one received a notification encouraging a tip (below left), and a third got a notification that included the number of other riders in the area that had tipped last month (below right).

The effect was undeniable: After a two-week experiment, riders tipped an additional $3.48 per ride compared with riders who didn’t receive this notification. (In fact, both variants of the test increased the number of tips and the tip value.) Sledge says that the test proves that riders want to tip, and that reminding them to do so in the short window after they leave their ride can help them make good on that desire.

With that in mind, Sledge set out to encourage the default tip function, which allows riders to set a tip amount for every ride they take. The test ran similarly: Push notifications were sent out to millions of riders. The push notifications led to the ride history screen, or the default tips screen (below).

After two weeks, riders tipped an additional $6 on rides compared with people who didn’t receive the notification, and the number of riders setting a default tip for all their drivers increased 4,000% or 41x.

So what’s next to try to help increase tips for Lyft drivers? Sledge says the team has already updated the tipping screen to make it more engaging and clear to riders why they might tip. He also said they’d like to personalize notifications so that a rider can celebrate a driver’s milestone, whether it’s a great rating, a 15,000th ride, or even their birthday. “We’ve learned that people want to tip,” says Sledge. “Now it’s all about making it easy for them to do it in a way that feels seamless and personal.”