Initial data commit

Task/Diversity-prediction-theorem/JavaScript/diversity-prediction-theorem-1.js

@@ -0,0 +1,33 @@
+'use strict';
+
+function sum(array) {
+    return array.reduce(function (a, b) {
+        return a + b;
+    });
+}
+
+function square(x) {
+    return x * x;
+}
+
+function mean(array) {
+    return sum(array) / array.length;
+}
+
+function averageSquareDiff(a, predictions) {
+    return mean(predictions.map(function (x) {
+        return square(x - a);
+    }));
+}
+
+function diversityTheorem(truth, predictions) {
+    var average = mean(predictions);
+    return {
+        'average-error': averageSquareDiff(truth, predictions),
+        'crowd-error': square(truth - average),
+        'diversity': averageSquareDiff(average, predictions)
+    };
+}
+
+console.log(diversityTheorem(49, [48,47,51]))
+console.log(diversityTheorem(49, [48,47,51,42]))