We are living in a time of unprecedented levels of data collection. Everything around us is being tracked, recorded, and documented constantly, and in ways we may not even fully grasp. But in the giant “data ecosystem” where this information goes to live, there exist certain spaces that are curiously empty. We’ve gotten so accustomed to the ubiquity of data that these “missing datasets” leave us scratching our heads. Enter: Mimi Onuoha. There’s always a reason behind it, she says, when certain information is being collected and saved while other information is not. Join Onuoha as she reveals common patterns behind these data absences; ways missing datasets have been used systematically to disadvantage certain groups; and ways in which data can be used as a measure for change.