Great question Tom, and at this point I don't believe there is a hard and fast answer. I would start with the basic assumption that EBOM has to be somewhat limited in scope to 'commuting' behavior, that is, trips to and from the workplace or school. For your building, I would focus the survey on the working population and school-age children, and exclude non-working adults (retirees or stay-at-home parents) and pre-school age children. Obviously, you'll have to make some thoughtful accommodations for various carpool and public transit situations that arise in a residential environment, but I think that if you keep the credit intent in mind while designing your survey, you can get a result that the reviewer will find convincing. Ultimately, LEED 'wants' to award points to residential buildings that genuinely facilitate alternative transportation use, there just isn't an established pathway to do so written down in the Reference Guide.