[#12065] Student viewing rubric results: average doesn't match (#12066)

* Fix rubric stats calculation

* Fix tests

Author: zhaojj2209

src/web/app/components/question-types/question-statistics/question-statistics-calculation/rubric-question-statistics-calculation.ts

@@ -124,18 +124,19 @@ export class RubricQuestionStatisticsCalculation
     for (const recipient of Object.keys(this.perRecipientStatsMap)) {
       const perRecipientStats: PerRecipientStats = this.perRecipientStatsMap[recipient];
 
+      // Answers sum = number of answers in each column
       perRecipientStats.answersSum = this.calculateAnswersSum(perRecipientStats.answers);
       perRecipientStats.percentages = this.calculatePercentages(perRecipientStats.answers);
-      perRecipientStats.percentagesAverage =
-          this.calculatePercentagesAverage(perRecipientStats.percentages,
-          this.calculateNumResponses(perRecipientStats.answersSum));
+      perRecipientStats.percentagesAverage = this.calculatePercentagesAverage(perRecipientStats.answersSum);
       perRecipientStats.subQuestionWeightAverage =
           this.calculateSubQuestionWeightAverage(perRecipientStats.answers);
       perRecipientStats.weightsAverage = this.calculateWeightsAverage(this.weights);
-      perRecipientStats.overallWeightedSum = this.calculateWeightedSum(perRecipientStats.percentagesAverage,
-          perRecipientStats.answersSum, perRecipientStats.weightsAverage);
+      // Overall weighted sum = sum of total chosen weight for all sub questions
+      perRecipientStats.overallWeightedSum =
+        +(perRecipientStats.subQuestionTotalChosenWeight.reduce((a, b) => a + b)).toFixed(2);
+      // Overall weighted average = overall weighted sum / total number of responses
       perRecipientStats.overallWeightAverage = +(perRecipientStats.overallWeightedSum
-          / (this.calculateNumResponses(perRecipientStats.answersSum))).toFixed(2);
+          / this.calculateNumResponses(perRecipientStats.answersSum)).toFixed(2);
     }
   }
 
@@ -195,32 +196,19 @@ export class RubricQuestionStatisticsCalculation
   }
 
   // Calculate percentage average for each column
-  private calculatePercentagesAverage(percentages: number[][], numAnswers: number): number[] {
-    // Calculate sum of percentages for each column
-    const sums: number[] = this.calculateAnswersSum(percentages);
+  private calculatePercentagesAverage(answersSum: number[]): number[] {
+    // Calculate total number of responses
+    const numResponses = this.calculateNumResponses(answersSum);
     const averages: number[] = [];
-    // Divide each percentage by the number of answers
-    for (let i: number = 0; i < sums.length; i += 1) {
-      averages[i] = numAnswers === 0 ? 0 : +(sums[i] / numAnswers).toFixed(2);
+    // Divide each column sum by total number of responses, then convert to percentage
+    for (let i: number = 0; i < answersSum.length; i += 1) {
+      averages[i] = numResponses === 0 ? 0 : +(answersSum[i] * 100 / numResponses).toFixed(2);
     }
     return averages;
   }
 
-  // Calculate weighted sum of responses
-  private calculateWeightedSum(percentages: number[], answers: number[], weights: number[]): number {
-    let sum: number = 0;
-    for (let i: number = 0; i < answers.length; i += 1) {
-      sum += (percentages[i] / 100) * answers[i] * weights[i];
-    }
-    return +sum.toFixed(2);
-  }
-
   // Calculate total number of responses
   private calculateNumResponses(answersSum: number[]): number {
-    let num: number = 0;
-    for (let i = 0; i < answersSum.length; i += 1) {
-      num += answersSum[i];
-    }
-    return num;
+    return answersSum.reduce((a, b) => a + b);
   }
 }

src/web/app/components/question-types/question-statistics/test-data/rubricQuestionResponses.json

@@ -66,15 +66,15 @@
       "percentages": [
         [50, 50], [50, 50], [100, 0]
       ],
-      "percentagesAverage": [33.33, 16.67],
+      "percentagesAverage": [66.67, 33.33],
       "recipientEmail": "[email protected]",
       "recipientName": "Alice",
       "recipientTeam": "Team 1",
       "subQuestionTotalChosenWeight": [1, 1, 0.8],
       "subQuestionWeightAverage": [0.5, 0.5, 0.4],
       "weightsAverage": [0.23, 0.77],
-      "overallWeightedSum": 0.56,
-      "overallWeightAverage": 0.09
+      "overallWeightedSum": 2.8,
+      "overallWeightAverage": 0.47
     },
     "Bob": {
       "answers": [
@@ -84,15 +84,15 @@
       "percentages": [
         [100, 0], [50, 50], [100, 0]
       ],
-      "percentagesAverage": [41.67, 8.33],
+      "percentagesAverage": [83.33, 16.67],
       "recipientEmail": "[email protected]",
       "recipientName": "Bob",
       "recipientTeam": "Team 2",
       "subQuestionTotalChosenWeight": [0.4, 1, 0.8],
       "subQuestionWeightAverage": [0.2, 0.5, 0.4],
       "weightsAverage": [0.23, 0.77],
-      "overallWeightedSum": 0.54,
-      "overallWeightAverage": 0.09
+      "overallWeightedSum": 2.2,
+      "overallWeightAverage": 0.37
     }
   }
 }

src/web/services/__snapshots__/session-result-csv.service.spec.ts.snap

@@ -392,8 +392,8 @@ Team,Recipient Name,Recipient Email,Sub Question,Yes,No,Total,Average
 
 Per Recipient Statistics (Overall)
 Team,Recipient Name,Recipient Email,Yes,No,Total,Average
-\\"Team 1.1</td></div>'\\"\\"\\",\\"student1 In Course1</td></div>'\\"\\"\\",[email protected],50% (1) [1.25],50% (1) [-1.7],-0.22,-0.11
-\\"Team 1.1</td></div>'\\"\\"\\",student2 In Course1,[email protected],50% (1) [1.25],50% (1) [-1.7],-0.22,-0.11
+\\"Team 1.1</td></div>'\\"\\"\\",\\"student1 In Course1</td></div>'\\"\\"\\",[email protected],50% (1) [1.25],50% (1) [-1.7],-0.45,-0.23
+\\"Team 1.1</td></div>'\\"\\"\\",student2 In Course1,[email protected],50% (1) [1.25],50% (1) [-1.7],-0.45,-0.23
 \\"Team 1.1</td></div>'\\"\\"\\",student3 In Course1,[email protected],100% (2) [1.25],0% (0) [-1.7],2.5,1.25
 \\"Team 1.1</td></div>'\\"\\"\\",student4 In Course1,[email protected],100% (1) [1.25],0% (0) [-1.7],1.25,1.25