dirty commit: can't get references to work correctly between any tables

app/models/dashboard/response_rate_calculator.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module Dashboard
+  class ResponseRateCalculator
+    TEACHER_RATE_THRESHOLD = 25
+    STUDENT_RATE_THRESHOLD = 25
+    attr_reader :subcategory, :school, :academic_year
+
+    def initialize(subcategory:, school:, academic_year:)
+      @subcategory = subcategory
+      @school = school
+      @academic_year = academic_year
+    end
+
+    def rate
+      return 100 if population_data_unavailable?
+
+      return 0 unless survey_items_have_sufficient_responses?
+
+      return 0 unless total_possible_responses.positive?
+
+      cap_at_one_hundred(raw_response_rate).round
+    end
+
+    def meets_student_threshold?
+      rate >= STUDENT_RATE_THRESHOLD
+    end
+
+    def meets_teacher_threshold?
+      rate >= TEACHER_RATE_THRESHOLD
+    end
+
+    private
+
+    def cap_at_one_hundred(response_rate)
+      response_rate > 100 ? 100 : response_rate
+    end
+
+    def average_responses_per_survey_item
+      response_count / survey_item_count.to_f
+    end
+
+    def respondents
+      @respondents ||= Respondent.by_school_and_year(school:, academic_year:)
+    end
+
+    def population_data_unavailable?
+      @population_data_unavailable ||= respondents.nil?
+    end
+  end
+end