diff --git a/Modules/Filtering/Path/include/itkContourExtractor2DImageFilter.hxx b/Modules/Filtering/Path/include/itkContourExtractor2DImageFilter.hxx
index a123581f5b9..cc55c8310f9 100644
--- a/Modules/Filtering/Path/include/itkContourExtractor2DImageFilter.hxx
+++ b/Modules/Filtering/Path/include/itkContourExtractor2DImageFilter.hxx
@@ -394,11 +394,11 @@ ContourExtractor2DImageFilter<TInputImage>::GenerateDataForLabels()
 
 
 template <typename TInputImage>
-inline typename ContourExtractor2DImageFilter<TInputImage>::VertexType
+inline auto
 ContourExtractor2DImageFilter<TInputImage>::InterpolateContourPosition(InputPixelType  fromValue,
                                                                        InputPixelType  toValue,
                                                                        InputIndexType  fromIndex,
-                                                                       InputOffsetType toOffset)
+                                                                       InputOffsetType toOffset) -> VertexType
 {
   // Now calculate the fraction of the way from 'from' to 'to' that the contour
   // crosses. Interpolate linearly: y = v0 + (v1 - v0) * x, and solve for the
diff --git a/Modules/Numerics/Statistics/include/itkImageToListSampleAdaptor.hxx b/Modules/Numerics/Statistics/include/itkImageToListSampleAdaptor.hxx
index 68261774280..3044020440e 100644
--- a/Modules/Numerics/Statistics/include/itkImageToListSampleAdaptor.hxx
+++ b/Modules/Numerics/Statistics/include/itkImageToListSampleAdaptor.hxx
@@ -56,8 +56,7 @@ ImageToListSampleAdaptor<TImage>::Size() const -> InstanceIdentifier
 }
 
 template <typename TImage>
-inline typename ImageToListSampleAdaptor<TImage>::AbsoluteFrequencyType ImageToListSampleAdaptor<TImage>::GetFrequency(
-  InstanceIdentifier) const
+inline auto ImageToListSampleAdaptor<TImage>::GetFrequency(InstanceIdentifier) const -> AbsoluteFrequencyType
 {
   if (m_Image.IsNull())
   {
diff --git a/Modules/Numerics/Statistics/include/itkJointDomainImageToListSampleAdaptor.hxx b/Modules/Numerics/Statistics/include/itkJointDomainImageToListSampleAdaptor.hxx
index e740dc22727..e980b18ffa7 100644
--- a/Modules/Numerics/Statistics/include/itkJointDomainImageToListSampleAdaptor.hxx
+++ b/Modules/Numerics/Statistics/include/itkJointDomainImageToListSampleAdaptor.hxx
@@ -45,8 +45,7 @@ JointDomainImageToListSampleAdaptor<TImage>::Size() const -> InstanceIdentifier
 }
 
 template <typename TImage>
-inline typename JointDomainImageToListSampleAdaptor<TImage>::AbsoluteFrequencyType
-  JointDomainImageToListSampleAdaptor<TImage>::GetFrequency(InstanceIdentifier) const
+inline auto JointDomainImageToListSampleAdaptor<TImage>::GetFrequency(InstanceIdentifier) const -> AbsoluteFrequencyType
 {
   if (m_Image.IsNull())
   {
diff --git a/Modules/Numerics/Statistics/include/itkKdTreeGenerator.hxx b/Modules/Numerics/Statistics/include/itkKdTreeGenerator.hxx
index 370b3f7f378..2a0b95af9e2 100644
--- a/Modules/Numerics/Statistics/include/itkKdTreeGenerator.hxx
+++ b/Modules/Numerics/Statistics/include/itkKdTreeGenerator.hxx
@@ -113,12 +113,12 @@ KdTreeGenerator<TSample>::GenerateData()
 }
 
 template <typename TSample>
-inline typename KdTreeGenerator<TSample>::KdTreeNodeType *
+inline auto
 KdTreeGenerator<TSample>::GenerateNonterminalNode(unsigned int            beginIndex,
                                                   unsigned int            endIndex,
                                                   MeasurementVectorType & lowerBound,
                                                   MeasurementVectorType & upperBound,
-                                                  unsigned int            level)
+                                                  unsigned int            level) -> KdTreeNodeType *
 {
   using NodeType = typename KdTreeType::KdTreeNodeType;
   MeasurementType dimensionLowerBound;
@@ -184,12 +184,12 @@ KdTreeGenerator<TSample>::GenerateNonterminalNode(unsigned int            beginI
 }
 
 template <typename TSample>
-inline typename KdTreeGenerator<TSample>::KdTreeNodeType *
+inline auto
 KdTreeGenerator<TSample>::GenerateTreeLoop(unsigned int            beginIndex,
                                            unsigned int            endIndex,
                                            MeasurementVectorType & lowerBound,
                                            MeasurementVectorType & upperBound,
-                                           unsigned int            level)
+                                           unsigned int            level) -> KdTreeNodeType *
 {
   if (endIndex - beginIndex <= m_BucketSize)
   {
diff --git a/Modules/Numerics/Statistics/include/itkPointSetToListSampleAdaptor.hxx b/Modules/Numerics/Statistics/include/itkPointSetToListSampleAdaptor.hxx
index 580fa1cd71c..82c2c543b62 100644
--- a/Modules/Numerics/Statistics/include/itkPointSetToListSampleAdaptor.hxx
+++ b/Modules/Numerics/Statistics/include/itkPointSetToListSampleAdaptor.hxx
@@ -96,8 +96,7 @@ PointSetToListSampleAdaptor<TPointSet>::GetMeasurementVector(InstanceIdentifier
 }
 
 template <typename TPointSet>
-inline typename PointSetToListSampleAdaptor<TPointSet>::AbsoluteFrequencyType
-  PointSetToListSampleAdaptor<TPointSet>::GetFrequency(InstanceIdentifier) const
+inline auto PointSetToListSampleAdaptor<TPointSet>::GetFrequency(InstanceIdentifier) const -> AbsoluteFrequencyType
 {
   if (m_PointSet.IsNull())
   {
diff --git a/Modules/Numerics/Statistics/include/itkVectorContainerToListSampleAdaptor.hxx b/Modules/Numerics/Statistics/include/itkVectorContainerToListSampleAdaptor.hxx
index 05e787b8e88..775093d37e3 100644
--- a/Modules/Numerics/Statistics/include/itkVectorContainerToListSampleAdaptor.hxx
+++ b/Modules/Numerics/Statistics/include/itkVectorContainerToListSampleAdaptor.hxx
@@ -63,8 +63,8 @@ VectorContainerToListSampleAdaptor<TVectorContainer>::GetMeasurementVector(Insta
 }
 
 template <typename TVectorContainer>
-inline typename VectorContainerToListSampleAdaptor<TVectorContainer>::AbsoluteFrequencyType
-  VectorContainerToListSampleAdaptor<TVectorContainer>::GetFrequency(InstanceIdentifier) const
+inline auto VectorContainerToListSampleAdaptor<TVectorContainer>::GetFrequency(InstanceIdentifier) const
+  -> AbsoluteFrequencyType
 {
   if (this->m_VectorContainer.IsNull())
   {
diff --git a/Modules/Numerics/Statistics/include/itkWeightedCentroidKdTreeGenerator.hxx b/Modules/Numerics/Statistics/include/itkWeightedCentroidKdTreeGenerator.hxx
index cc0396fcc9a..f1d6fb23648 100644
--- a/Modules/Numerics/Statistics/include/itkWeightedCentroidKdTreeGenerator.hxx
+++ b/Modules/Numerics/Statistics/include/itkWeightedCentroidKdTreeGenerator.hxx
@@ -32,12 +32,12 @@ WeightedCentroidKdTreeGenerator<TSample>::PrintSelf(std::ostream & os, Indent in
 }
 
 template <typename TSample>
-inline typename WeightedCentroidKdTreeGenerator<TSample>::KdTreeNodeType *
+inline auto
 WeightedCentroidKdTreeGenerator<TSample>::GenerateNonterminalNode(unsigned int            beginIndex,
                                                                   unsigned int            endIndex,
                                                                   MeasurementVectorType & lowerBound,
                                                                   MeasurementVectorType & upperBound,
-                                                                  unsigned int            level)
+                                                                  unsigned int            level) -> KdTreeNodeType *
 {
   MeasurementType dimensionLowerBound;
   MeasurementType dimensionUpperBound;