Merge pull request #2975 from betagouv/percentiles

Calcul du temps de traitement estimé d'un dossier avec des percentiles

app/assets/stylesheets/new_design/status_overview.scss

@@ -51,7 +51,7 @@
   .brouillon,
   .en-construction,
   .en-instruction {
-    max-width: 600px;
+    max-width: 650px;
     margin: auto;
   }
 

app/models/procedure.rb

@@ -1,3 +1,5 @@
+require Rails.root.join('lib', 'percentile')
+
 class Procedure < ApplicationRecord
   MAX_DUREE_CONSERVATION = 36
 
@@ -304,16 +306,16 @@ class Procedure < ApplicationRecord
     end
   end
 
-  def mean_traitement_time
-    mean_time(:en_construction_at, :processed_at)
+  def usual_traitement_time
+    percentile_time(:en_construction_at, :processed_at, 90)
   end
 
-  def mean_verification_time
-    mean_time(:en_construction_at, :en_instruction_at)
+  def usual_verification_time
+    percentile_time(:en_construction_at, :en_instruction_at, 90)
   end
 
-  def mean_instruction_time
-    mean_time(:en_instruction_at, :processed_at)
+  def usual_instruction_time
+    percentile_time(:en_instruction_at, :processed_at, 90)
   end
 
   PATH_AVAILABLE = :available
@@ -421,14 +423,14 @@ class Procedure < ApplicationRecord
     true
   end
 
-  def mean_time(start_attribute, end_attribute)
+  def percentile_time(start_attribute, end_attribute, p)
     times = dossiers
       .state_termine
       .pluck(start_attribute, end_attribute)
       .map { |(start_date, end_date)| end_date - start_date }
 
     if times.present?
-      times.sum.fdiv(times.size).ceil
+      times.percentile(p).ceil
     end
   end
 end

app/views/new_user/dossiers/show/_status_overview.html.haml

@@ -31,10 +31,10 @@
             %strong votre dossier passera directement en instruction
 
         / FIXME: remove the custom procedure switch at some point
-        - if dossier.procedure.mean_verification_time && show_time_means
+        - if dossier.procedure.usual_verification_time && show_time_means
           - cache(dossier.procedure, expires_in: 1.week) do
             %p
-              Le temps moyen de vérification pour cette démarche est de #{distance_of_time_in_words(dossier.procedure.mean_verification_time)}.
+              Habituellement, les dossiers de cette démarche sont vérifiés dans un délai de #{distance_of_time_in_words(dossier.procedure.usual_verification_time)}.
 
     - elsif dossier.en_instruction?
       .en-instruction
@@ -46,10 +46,10 @@
           avec le résultat.
 
         / FIXME: remove the custom procedure switch at some point
-        - if dossier.procedure.mean_instruction_time && show_time_means
+        - if dossier.procedure.usual_instruction_time && show_time_means
           - cache(dossier.procedure, expires_in: 1.week) do
             %p
-              Le temps moyen d’instruction pour cette démarche est de #{distance_of_time_in_words(dossier.procedure.mean_instruction_time)}.
+              Habituellement, les dossiers de cette démarche sont traités dans un délai de #{distance_of_time_in_words(dossier.procedure.usual_instruction_time)}.
 
     - elsif dossier.accepte?
       .accepte

lib/percentile.rb

@@ -0,0 +1,31 @@
+# Adapted from https://github.com/thirtysixthspan/descriptive_statistics
+
+# Copyright (c) 2010-2014 Derrick Parkhurst (derrick.parkhurst@gmail.com)
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+
+class Array
+  def percentile(p)
+    values = self.sort
+
+    if values.empty?
+      return []
+    elsif values.size == 1
+      return values.first
+    elsif p == 100
+      return values.last
+    end
+
+    rank = p / 100.0 * (values.size - 1)
+    lower, upper = values[rank.floor, 2]
+    lower + (upper - lower) * (rank - rank.floor)
+  end
+end

spec/features/new_user/dossier_details_spec.rb

@@ -23,7 +23,7 @@ describe 'Dossier details:' do
         visit dossier_path(dossier)
       end
 
-      it { expect(page).to have_text("Le temps moyen de vérification pour cette démarche est de 10 jours.") }
+      it { expect(page).to have_text("Habituellement, les dossiers de cette démarche sont vérifiés dans un délai de 10 jours.") }
     end
 
     context "when the dossier is in instruction" do
@@ -34,7 +34,7 @@ describe 'Dossier details:' do
         visit dossier_path(dossier)
       end
 
-      it { expect(page).to have_text("Le temps moyen d’instruction pour cette démarche est de 2 mois.") }
+      it { expect(page).to have_text("Habituellement, les dossiers de cette démarche sont traités dans un délai de 2 mois.") }
     end
   end
 

spec/models/procedure_spec.rb

@@ -705,22 +705,34 @@ describe Procedure do
     end
   end
 
-  describe '#mean_instruction_time' do
+  describe '#usual_instruction_time' do
     let(:procedure) { create(:procedure) }
 
-    context 'when there is only one dossier' do
-      let(:dossier) { create(:dossier, procedure: procedure) }
-
-      context 'which is termine' do
-        before do
-          dossier.accepte!
-          processed_date = Time.zone.parse('12/12/2012')
-          instruction_date = processed_date - 1.day
-          dossier.update(en_instruction_at: instruction_date, processed_at: processed_date)
-        end
-
-        it { expect(procedure.mean_instruction_time).to eq(1.day.to_i) }
+    before do
+      processed_delays.each do |delay|
+        dossier = create :dossier, :accepte, procedure: procedure
+        instruction_date = 1.month.ago
+        processed_date = instruction_date + delay
+        dossier.update!(en_instruction_at: instruction_date, processed_at: processed_date)
       end
     end
+
+    context 'when there are several processed dossiers' do
+      let(:processed_delays) { [1.day, 2.days, 2.days, 2.days, 2.days, 3.days, 3.days, 3.days, 3.days, 12.days] }
+
+      it 'returns a time representative of the dossier instruction delay' do
+        expect(procedure.usual_instruction_time).to be_between(3.days, 4.days)
+      end
+    end
+
+    context 'when there is only one processed dossier' do
+      let(:processed_delays) { [1.day] }
+      it { expect(procedure.usual_instruction_time).to eq(1.day) }
+    end
+
+    context 'where there is no processed dossier' do
+      let(:processed_delays) { [] }
+      it { expect(procedure.usual_instruction_time).to be_nil }
+    end
   end
 end