Index: Ringtoets/Common/test/Ringtoets.Common.Data.Test/Probabilistics/DeterministicDesignVariableTest.cs
===================================================================
diff -u -r3178e116f5e59e03078d465efeb303c5e232c7bf -ra0572592dd67440ce73130886d9db5d1bd1d2afb
--- Ringtoets/Common/test/Ringtoets.Common.Data.Test/Probabilistics/DeterministicDesignVariableTest.cs	(.../DeterministicDesignVariableTest.cs)	(revision 3178e116f5e59e03078d465efeb303c5e232c7bf)
+++ Ringtoets/Common/test/Ringtoets.Common.Data.Test/Probabilistics/DeterministicDesignVariableTest.cs	(.../DeterministicDesignVariableTest.cs)	(revision a0572592dd67440ce73130886d9db5d1bd1d2afb)
@@ -44,50 +44,13 @@
             var designVariable = new DeterministicDesignVariable<IDistribution>(distribution);
 
             // Assert
+            Assert.IsInstanceOf<DesignVariable<IDistribution>>(designVariable);
             Assert.AreSame(distribution, designVariable.Distribution);
             Assert.AreEqual(0, designVariable.GetDesignValue().Value);
             mocks.VerifyAll();
         }
 
         [Test]
-        public void ParameteredConstructor_DistributionIsNull_ThrowArgumentNullException()
-        {
-            // Call
-            TestDelegate call = () => new DeterministicDesignVariable<IDistribution>(null);
-
-            // Assert
-            var exception = Assert.Throws<ArgumentNullException>(call);
-            string customMessagePart = exception.Message.Split(new[]
-            {
-                Environment.NewLine
-            }, StringSplitOptions.None)[0];
-            Assert.AreEqual("Een kansverdeling moet opgegeven zijn om op basis van die data een rekenwaarde te bepalen.", customMessagePart);
-        }
-
-        [Test]
-        public void Distribution_SetToNull_ThrowArgumentNullException()
-        {
-            // Setup
-            var mocks = new MockRepository();
-            var distribution = mocks.StrictMock<IDistribution>();
-            mocks.ReplayAll();
-
-            var designVariable = new DeterministicDesignVariable<IDistribution>(distribution);
-
-            // Call
-            TestDelegate call = () => designVariable.Distribution = null;
-
-            // Assert
-            var exception = Assert.Throws<ArgumentNullException>(call);
-            string customMessagePart = exception.Message.Split(new[]
-            {
-                Environment.NewLine
-            }, StringSplitOptions.None)[0];
-            Assert.AreEqual("Een kansverdeling moet opgegeven zijn om op basis van die data een rekenwaarde te bepalen.", customMessagePart);
-            mocks.VerifyAll(); // Expect no calls on mocks
-        }
-
-        [Test]
         public void GetDesignValue_Always_ReturnsDeterministicValueWithNumberOfDecimalsFromDistributionMean()
         {
             // Setup
Index: Ringtoets/Common/test/Ringtoets.Common.Data.Test/Probabilistics/LogNormalDistributionDesignVariableTest.cs
===================================================================
diff -u -rb3b6c13cf736c134476b3db34281332d01ca86b1 -ra0572592dd67440ce73130886d9db5d1bd1d2afb
--- Ringtoets/Common/test/Ringtoets.Common.Data.Test/Probabilistics/LogNormalDistributionDesignVariableTest.cs	(.../LogNormalDistributionDesignVariableTest.cs)	(revision b3b6c13cf736c134476b3db34281332d01ca86b1)
+++ Ringtoets/Common/test/Ringtoets.Common.Data.Test/Probabilistics/LogNormalDistributionDesignVariableTest.cs	(.../LogNormalDistributionDesignVariableTest.cs)	(revision a0572592dd67440ce73130886d9db5d1bd1d2afb)
@@ -37,11 +37,12 @@
             var logNormalDistribution = new LogNormalDistribution(2);
 
             // Call
-            var designValue = new LogNormalDistributionDesignVariable(logNormalDistribution);
+            var designVariable = new LogNormalDistributionDesignVariable(logNormalDistribution);
 
             // Assert
-            Assert.AreSame(logNormalDistribution, designValue.Distribution);
-            Assert.AreEqual(0.5, designValue.Percentile);
+            Assert.IsInstanceOf<PercentileBasedDesignVariable<LogNormalDistribution>>(designVariable);
+            Assert.AreSame(logNormalDistribution, designVariable.Distribution);
+            Assert.AreEqual(0.5, designVariable.Percentile);
         }
 
         /// <summary>
Index: Ringtoets/Common/test/Ringtoets.Common.Data.Test/Probabilistics/NormalDistributionDesignVariableTest.cs
===================================================================
diff -u -rb3b6c13cf736c134476b3db34281332d01ca86b1 -ra0572592dd67440ce73130886d9db5d1bd1d2afb
--- Ringtoets/Common/test/Ringtoets.Common.Data.Test/Probabilistics/NormalDistributionDesignVariableTest.cs	(.../NormalDistributionDesignVariableTest.cs)	(revision b3b6c13cf736c134476b3db34281332d01ca86b1)
+++ Ringtoets/Common/test/Ringtoets.Common.Data.Test/Probabilistics/NormalDistributionDesignVariableTest.cs	(.../NormalDistributionDesignVariableTest.cs)	(revision a0572592dd67440ce73130886d9db5d1bd1d2afb)
@@ -30,17 +30,18 @@
     public class NormalDistributionDesignVariableTest
     {
         [Test]
-        public void ParameterdConstructor_ValidLogNormalDistribution_ExpectedValues()
+        public void ParameterdConstructor_ValidNormalDistribution_ExpectedValues()
         {
             // Setup
             var normalDistribution = new NormalDistribution(3);
 
             // Call
-            var designValue = new NormalDistributionDesignVariable(normalDistribution);
+            var designVariable = new NormalDistributionDesignVariable(normalDistribution);
 
             // Assert
-            Assert.AreSame(normalDistribution, designValue.Distribution);
-            Assert.AreEqual(0.5, designValue.Percentile);
+            Assert.IsInstanceOf<PercentileBasedDesignVariable<NormalDistribution>>(designVariable);
+            Assert.AreSame(normalDistribution, designVariable.Distribution);
+            Assert.AreEqual(0.5, designVariable.Percentile);
         }
 
         /// <summary>
Index: Ringtoets/Common/test/Ringtoets.Common.Data.Test/Probabilistics/VariationCoefficientLogNormalDistributionDesignVariableTest.cs
===================================================================
diff -u -rb3b6c13cf736c134476b3db34281332d01ca86b1 -ra0572592dd67440ce73130886d9db5d1bd1d2afb
--- Ringtoets/Common/test/Ringtoets.Common.Data.Test/Probabilistics/VariationCoefficientLogNormalDistributionDesignVariableTest.cs	(.../VariationCoefficientLogNormalDistributionDesignVariableTest.cs)	(revision b3b6c13cf736c134476b3db34281332d01ca86b1)
+++ Ringtoets/Common/test/Ringtoets.Common.Data.Test/Probabilistics/VariationCoefficientLogNormalDistributionDesignVariableTest.cs	(.../VariationCoefficientLogNormalDistributionDesignVariableTest.cs)	(revision a0572592dd67440ce73130886d9db5d1bd1d2afb)
@@ -37,11 +37,12 @@
             var logNormalDistribution = new VariationCoefficientLogNormalDistribution(2);
 
             // Call
-            var designValue = new VariationCoefficientLogNormalDistributionDesignVariable(logNormalDistribution);
+            var designVariable = new VariationCoefficientLogNormalDistributionDesignVariable(logNormalDistribution);
 
             // Assert
-            Assert.AreSame(logNormalDistribution, designValue.Distribution);
-            Assert.AreEqual(0.5, designValue.Percentile);
+            Assert.IsInstanceOf<VariationCoefficientDesignVariable<VariationCoefficientLogNormalDistribution>>(designVariable);
+            Assert.AreSame(logNormalDistribution, designVariable.Distribution);
+            Assert.AreEqual(0.5, designVariable.Percentile);
         }
 
         /// <summary>