diff --git a/gtsam/discrete/DecisionTreeFactor.h b/gtsam/discrete/DecisionTreeFactor.h
index f1df7ae03..f759c10f3 100644
--- a/gtsam/discrete/DecisionTreeFactor.h
+++ b/gtsam/discrete/DecisionTreeFactor.h
@@ -97,7 +97,7 @@ namespace gtsam {
     /// @name Standard Interface
     /// @{
 
-    /// Value is just look up in AlgebraicDecisonTree
+    /// Value is just look up in AlgebraicDecisionTree.
     double operator()(const DiscreteValues& values) const override {
       return ADT::operator()(values);
     }
diff --git a/gtsam/discrete/DiscreteFactor.cpp b/gtsam/discrete/DiscreteFactor.cpp
index 08309e2e1..c60594f57 100644
--- a/gtsam/discrete/DiscreteFactor.cpp
+++ b/gtsam/discrete/DiscreteFactor.cpp
@@ -19,6 +19,7 @@
 
 #include <gtsam/base/Vector.h>
 #include <gtsam/discrete/DiscreteFactor.h>
+#include <gtsam/hybrid/HybridValues.h>
 
 #include <cmath>
 #include <sstream>
@@ -27,6 +28,21 @@ using namespace std;
 
 namespace gtsam {
 
+/* ************************************************************************* */
+const DiscreteValues& GetDiscreteValues(const HybridValues& c) {
+  return c.discrete();
+}
+
+/* ************************************************************************* */
+double DiscreteFactor::error(const DiscreteValues& values) const {
+  return -std::log((*this)(values));
+}
+
+/* ************************************************************************* */
+double DiscreteFactor::error(const HybridValues& c) const {
+  return DiscreteFactor::error(GetDiscreteValues(c));
+}
+
 /* ************************************************************************* */
 std::vector<double> expNormalize(const std::vector<double>& logProbs) {
   double maxLogProb = -std::numeric_limits<double>::infinity();
diff --git a/gtsam/discrete/DiscreteFactor.h b/gtsam/discrete/DiscreteFactor.h
index c6bb079fb..dc0adbab4 100644
--- a/gtsam/discrete/DiscreteFactor.h
+++ b/gtsam/discrete/DiscreteFactor.h
@@ -27,6 +27,10 @@ namespace gtsam {
 
 class DecisionTreeFactor;
 class DiscreteConditional;
+class HybridValues;
+
+// Forward declaration of function to extract Values from HybridValues.
+const DiscreteValues& GetDiscreteValues(const HybridValues& c);
 
 /**
  * Base class for discrete probabilistic factors
@@ -83,6 +87,15 @@ public:
   /// Find value for given assignment of values to variables
   virtual double operator()(const DiscreteValues&) const = 0;
 
+  /// Error is just -log(value)
+  double error(const DiscreteValues& values) const;
+
+  /**
+   * The Factor::error simply extracts the \class DiscreteValues from the
+   * \class HybridValues and calculates the error.
+   */
+  double error(const HybridValues& c) const override;
+
   /// Multiply in a DecisionTreeFactor and return the result as DecisionTreeFactor
   virtual DecisionTreeFactor operator*(const DecisionTreeFactor&) const = 0;
 
diff --git a/gtsam/discrete/tests/testDecisionTreeFactor.cpp b/gtsam/discrete/tests/testDecisionTreeFactor.cpp
index 869b3c630..3dbb3e64f 100644
--- a/gtsam/discrete/tests/testDecisionTreeFactor.cpp
+++ b/gtsam/discrete/tests/testDecisionTreeFactor.cpp
@@ -48,6 +48,9 @@ TEST( DecisionTreeFactor, constructors)
   EXPECT_DOUBLES_EQUAL(8, f1(values), 1e-9);
   EXPECT_DOUBLES_EQUAL(7, f2(values), 1e-9);
   EXPECT_DOUBLES_EQUAL(75, f3(values), 1e-9);
+
+  // Assert that error = -log(value)
+  EXPECT_DOUBLES_EQUAL(-log(f1(values)), f1.error(values), 1e-9);
 }
 
 /* ************************************************************************* */