aggregated, "additive" data like population counts are summed up proportionally to the area of the intersection, "averages"
need further additive "parent" count variables to estimate weighted averages.'><meta property="og:image" content="https://mountainmath.github.io/tongfen/logo.png"><meta property="og:image:alt" content="tongfen"><meta name="twitter:card" content="summary_large_image"><meta name="twitter:creator" content="@vb_jens"><meta name="twitter:site" content="https://mountainmath.github.io/tongfen