fixes #1030

app/logical/reports/user_promotions.rb

@@ -0,0 +1,29 @@
+require 'statistics2'
+
+module Reports
+  class UserPromotions
+    def self.confidence_interval_for(user, n)
+      up_votes = Post.where("created_at >= ?", min_time).where(:uploader_id => user.id).where("fav_count >= ?", n).count
+      total_votes = Post.where("created_at >= ?", min_time).where(:uploader_id => user.id).count
+      ci_lower_bound(up_votes, total_votes, 0.95)
+    end
+
+    def self.ci_lower_bound(pos, n, confidence)
+      if n == 0
+        return 0
+      end
+
+      z = Statistics2.pnormaldist(1-(1-confidence)/2)
+      phat = 1.0*pos/n
+      100 * (phat + z*z/(2*n) - z * Math.sqrt((phat*(1-phat)+z*z/(4*n))/n))/(1+z*z/n)
+    end
+
+    def self.min_time
+      30.days.ago
+    end
+
+    def users
+      User.joins(:posts).where("users.level < ?", User::Levels::CONTRIBUTOR).where("posts.created_at >= ? and posts.fav_count >= 1", self.class.min_time).order("users.name")
+    end
+  end
+end