Abstract: The present invention is directed to a method and system for measuring the biologically based responses of an audience to a presentation that provides sensory stimulating experience and determining a measure of the level and pattern of engagement of that audience to the presentation. In particular, the invention is directed to a method and system for measuring one or more biologically based responses of one or more persons being exposed to the presentation in order to determine the moment-to-moment pattern and overall level of engagement. Further, the invention can be used to determine whether the presentation or the content in the presentation is more effective in a population relative to other presentations (or content) and other populations and to help identify elements of the presentation that contribute to the high level of engagement and the effectiveness and success of the presentation for that population.