You can calculate e for the case of the rider colliding with the elastic bumper by using the data you collected in this experiment. There are two menus for operating on the data shown on the screen: they are displayed underneath the graphs, and you can switch back and forth between them by pressing `N' for Next Menu and `P' for Previous Menu. Find the menu with the (C)ursor option and hit `C'. This draws a vertical line on the graphs which acts like a cursor: you can move it left and right with the arrow keys, and you can move more quickly if you hold down the control key at the same time. At the bottom of the screen, the x value (time) of the cursor and the two corresponding y values (displacement in the top graph, velocity in the bottom) are indicated more precisely than they can be read off the graphs. By moving the cursor to times a little bit before and after the collision with the elastic bumper (regions where the velocity is still constant), you can read off the values of the velocity at those times, and then calculate e.