24. The system of claim 23 , wherein the interest value comprises a selection score for the first article in a context of the first population group.
24. The system of claim 23 , wherein the interest value comprises a selection score for the first article in a context of the first population group. 25. The system of claim 24 , wherein the selection score for the first article in the context of the first population group comprises a number of clicks for the first article by members of the first population group for the search query.