chore: generate report of high number of nil grades in responses

lib/tasks/one_off.rake

@@ -140,4 +140,18 @@ namespace :one_off do
       academic_year.delete
     end
   end
+
+  desc "print out percentage of nil values for range"
+  task nil_grades: :environment do
+    AcademicYear.all.each do |academic_year|
+      School.all.each do |school|
+        total = SurveyItemResponse.where(school:, academic_year:,
+                                         survey_item: SurveyItem.student_survey_items).count.to_f
+        nil_count = SurveyItemResponse.where(school:, academic_year:, grade: nil,
+                                             survey_item: SurveyItem.student_survey_items).count
+        percentage = ((nil_count / total) * 100).round(1)
+        puts "#{percentage}% nil grades for:  #{school.name}, #{academic_year.range}" if percentage > 1
+      end
+    end
+  end
 end