That is a good point. We could somehow incorporate copy counts for eBooks, but that would not likely reflect a decline in popularity as there is no motivation to weed copies.

On Mon, Oct 14, 2013 at 4:18 PM, Joe Atzberger <> wrote:
Notably, boosting by holdings count will diminish the results for an eBook of the same popular title, assuming that one or zero "holdings" are associated with the eBook record (vs. many with the print version).  The same would be true for any electronic content, unless you adopted Marc's approach of tracking number of checkouts.

In our case, we use 3rd party commercial popularity data for the boost.