Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for generating rendering data that when rendered on a display device presents a graphical user interface that displays a first visual representation of a value curve, a time period selection window that is configured to move along the first visual representation of the value curve to select one or more portions of the first visual representation of the value curve, a second visual representation of the value curve that is based on the selected one or more portions of the first visual representation of the value curve, a first events bar that includes two or more first event icons that are each associated with a different type of event, and a second events bar that includes two or more second event icons that are each associated with a same type of event.