diff --git a/src/dkohl/util/RootMeanSquareError.java b/src/dkohl/util/RootMeanSquareError.java
new file mode 100644
index 0000000..3f10774
--- /dev/null
+++ b/src/dkohl/util/RootMeanSquareError.java
@@ -0,0 +1,35 @@
+package dkohl.util;
+
+import java.util.LinkedList;
+
+public class RootMeanSquareError {
+
+    private LinkedList<Double> expected;
+    private LinkedList<Double> groundTruth;
+    
+    public RootMeanSquareError() {
+	expected = new LinkedList<Double>();
+	groundTruth = new LinkedList<Double>();
+    }
+    
+    public void push(double predicted, double actual) {
+	expected.add(predicted);
+	groundTruth.add(actual);
+    }
+    
+    public double error() {
+	double mean = 0.0;
+	for(Double val : groundTruth) {
+	    mean += val;
+	}
+	mean /= groundTruth.size();
+	
+	double err = 0.0;
+	for(Double val : expected) {
+	    err += Math.pow(mean - val, 2);
+	}
+	return Math.sqrt(err);
+    }
+    
+    
+}