Social Media Marketing University (SMMU), an online training program for social media marketing, is celebrating Twitter’s eighth birthday with an infographic, exploring brands’ struggles on the platform.

The top concern it determined during a recent survey of more than 1,100 North American brands, was 41.5% of brands found measuring ROI on the platform difficult, however, 64.9% of them considered it an effective tool.

Other interesting insights from the survey include: 16.9% of brands don’t realize Twitter offers a paid platform, 62.4% use it to engage consumers during an event and only 2.4% of brands use the short-video off-shoot, Vine.

Check out more stats below. Click the image to enlarge it.