Modify score calculations. Ignore any survey item scores of 0.

Never include zero when performing calculations for scores.

app/models/measure.rb

@@ -50,20 +50,17 @@ class Measure < ActiveRecord::Base
       meets_student_threshold = sufficient_student_data?(school:, academic_year:)
       meets_teacher_threshold = sufficient_teacher_data?(school:, academic_year:)
       meets_admin_data_threshold = all_admin_data_collected?(school:, academic_year:)
-      lacks_sufficient_data = !meets_student_threshold && !meets_teacher_threshold && !includes_admin_data_items?
+      lacks_sufficient_survey_data = !meets_student_threshold && !meets_teacher_threshold
+      incalculable_score = lacks_sufficient_survey_data && !includes_admin_data_items?
 
-      next Score.new(nil, false, false, false) if lacks_sufficient_data
+      next Score.new(nil, false, false, false) if incalculable_score
 
       scores = []
-      scores << teacher_scales.map { |scale| scale.score(school:, academic_year:) }.average if meets_teacher_threshold
-      scores << student_scales.map { |scale| scale.score(school:, academic_year:) }.average if meets_student_threshold
-      if includes_admin_data_items?
-        scores << admin_data_items.map do |admin_data_item|
-          admin_value = admin_data_item.admin_data_values.where(school:, academic_year:).first
-          admin_value.likert_score if admin_value.present?
-        end
-      end
-      average = scores.flatten.compact.average
+      scores << collect_survey_scale_average(teacher_scales, school, academic_year) if meets_teacher_threshold
+      scores << collect_survey_scale_average(student_scales, school, academic_year) if meets_student_threshold
+      scores << collect_admin_scale_average(admin_data_items, school, academic_year) if includes_admin_data_items?
+
+      average = scores.flatten.compact.remove_zeros.average
 
       next Score.new(nil, false, false, false) if average.nan?
 
@@ -122,6 +119,17 @@ class Measure < ActiveRecord::Base
 
   private
 
+  def collect_survey_scale_average(scales, school, academic_year)
+    scales.map { |scale| scale.score(school:, academic_year:) }.average
+  end
+
+  def collect_admin_scale_average(scales, school, academic_year)
+    scales.map do |admin_data_item|
+      admin_value = admin_data_item.admin_data_values.where(school:, academic_year:).first
+      admin_value.likert_score if admin_value.present?
+    end
+  end
+
   def benchmark(name)
     averages = []
     averages << student_survey_items.first.send(name) if includes_student_survey_items?

app/models/scale.rb

@@ -8,12 +8,10 @@ class Scale < ApplicationRecord
     @score ||= Hash.new do |memo|
       memo[[school, academic_year]] = begin
         items = []
-        items << student_survey_items(school:, academic_year:)
-        items << teacher_survey_items
+        items << collect_survey_item_average(student_survey_items(school:, academic_year:), school, academic_year)
+        items << collect_survey_item_average(teacher_survey_items, school, academic_year)
 
-        items.flatten.map do |survey_item|
-          survey_item.score(school:, academic_year:)
-        end.average
+        items.remove_zeros.average
       end
     end
     @score[[school, academic_year]]
@@ -28,6 +26,12 @@ class Scale < ApplicationRecord
 
   private
 
+  def collect_survey_item_average(survey_items, school, academic_year)
+    survey_items.map do |survey_item|
+      survey_item.score(school:, academic_year:)
+    end.remove_zeros.average
+  end
+
   def teacher_survey_items
     survey_items.teacher_survey_items
   end

config/initializers/array_monkey_patches.rb

@@ -2,6 +2,10 @@ module ArrayMonkeyPatches
   def average
     sum.to_f / size
   end
+
+  def remove_zeros
+    reject { |item| item == 0 || item.to_f.nan? }
+  end
 end
 
 Array.include ArrayMonkeyPatches

doc/architectural_decision_records/9.md

@@ -0,0 +1,19 @@
+# Decision record 9
+
+# Modify score calculations so that a survey item score of 0 is never included in the average
+
+## Status
+
+Completed
+
+## Context
+
+Some scores were artificially low because survey items that lacked survey item responses returned a score of 0.  0 did not represent the average likert_scores of survey item responses, only the lack of responses.  0 was incorrectly being averaged with other survey items and artificially dragging down the score.
+
+## Decision
+
+Survey item scores of 0 should be ignored and filtered out when performing score calculations.
+
+## Consequences
+
+Some average scores have increased.

spec/models/scale_spec.rb

@@ -12,7 +12,9 @@ RSpec.describe Scale, type: :model do
     let(:teacher_survey_item_1) { create(:teacher_survey_item, scale:) }
     let(:teacher_survey_item_2) { create(:teacher_survey_item, scale:) }
     let(:teacher_survey_item_3) { create(:teacher_survey_item, scale:) }
+    let(:student_survey_item_1) { create(:student_survey_item, scale:) }
 
+    context 'when only teacher survey items exist' do
       before :each do
         create(:survey_item_response,
                survey_item: teacher_survey_item_1, academic_year:, school:, likert_score: 3)
@@ -21,7 +23,6 @@ RSpec.describe Scale, type: :model do
         create(:survey_item_response,
                survey_item: teacher_survey_item_3, academic_year:, school:, likert_score: 5)
       end
-
       it 'returns the average of the likert scores of the survey items' do
         expect(scale.score(school:, academic_year:)).to eq 4
       end
@@ -41,4 +42,35 @@ RSpec.describe Scale, type: :model do
         end
       end
     end
+
+    context 'when both teacher and student survey items exist' do
+      before :each do
+      create(:survey_item_response,
+             survey_item: teacher_survey_item_1, academic_year:, school:, likert_score: 3)
+      create(:survey_item_response,
+             survey_item: teacher_survey_item_2, academic_year:, school:, likert_score: 4)
+      create(:survey_item_response,
+             survey_item: teacher_survey_item_3, academic_year:, school:, likert_score: 5)
+      end
+      context 'but no survey item responses are linked to student survey items' do
+        before :each do
+          student_survey_item_1
+        end
+
+        it 'returns a score that only averages teacher survey items' do
+          expect(scale.score(school:, academic_year:)).to eq 4
+        end
+      end
+
+      context 'and some survey item responses exist for a student survey item' do
+        before :each do
+          create(:survey_item_response,
+                 survey_item: student_survey_item_1, academic_year:, school:, likert_score: 2)
+        end
+        it 'returns a score that gives equal weight to student and teacher survey items' do
+          expect(scale.score(school:, academic_year:)).to eq 3
+        end
+      end
+    end
+  end
 end