1. A computer program product tangibly embodied in a non-transitory machine-readable storage medium that includes instructions configured to be executed to cause a data processing apparatus to perform a method comprising: presenting a graphical display that shows a representation of values generated according to a penalized regression model for multiple parameters of a data set, wherein the represented values of the graphical display show a graph having a first axis that represents magnitudes of multiple parameter estimates of the penalized regression model and having a second axis that represents parameter estimate values of the multiple parameters of the penalized regression model; receiving a user input request for changing the graphical display of the representation of values, wherein the received user input request comprises a change to a parameter handle of the graphical display such that the change to the parameter handle indicates a change to at least one data parameter of the penalized regression model; calculating changes to the represented values of the penalized regression model in response to the received user input request; and changing the graphical display such that the changed graphical display shows a second representation of the values for the penalized regression model in accordance with the calculated changes.