45-use-statistical-testing

Using statistical testing to test whether the node has failed.

pkg/lib/stats.go

@@ -0,0 +1,39 @@
+// lib contains helper functions for the implementation
+package lib
+
+import (
+	"math"
+
+	"gonum.org/v1/gonum/stat"
+	"gonum.org/v1/gonum/stat/distuv"
+)
+
+// Modelling the distribution using a normal distribution get the count
+// of the outliers
+func GetOutliers[K comparable](counts map[K]uint64, alpha float64) []K {
+	n := float64(len(counts))
+
+	keys := MapKeys(counts)
+	values := make([]float64, len(keys))
+
+	for index, key := range keys {
+		values[index] = float64(counts[key])
+	}
+
+	mean := stat.Mean(values, nil)
+	stdDev := stat.StdDev(values, nil)
+
+	moe := distuv.Normal{Mu: 0, Sigma: 1}.Quantile(1-alpha/2) * (stdDev / math.Sqrt(n))
+
+	lowerBound := mean - moe
+
+	var outliers []K
+
+	for i, count := range values {
+		if count < lowerBound {
+			outliers = append(outliers, keys[i])
+		}
+	}
+
+	return outliers
+}