diff --git a/GUI/Model/Fit/FitParameterProxyModel.cpp b/GUI/Model/Fit/FitParameterModel.cpp
similarity index 80%
rename from GUI/Model/Fit/FitParameterProxyModel.cpp
rename to GUI/Model/Fit/FitParameterModel.cpp
index d2717a16bdaa2c3f12a0aa894459e5b58f57d724..8ad87fdf5cbf123b3c59773f02cfe5f42b7a1914 100644
--- a/GUI/Model/Fit/FitParameterProxyModel.cpp
+++ b/GUI/Model/Fit/FitParameterModel.cpp
@@ -2,17 +2,17 @@
 //
 //  BornAgain: simulate and fit reflection and scattering
 //
-//! @file      GUI/Model/Fit/FitParameterProxyModel.cpp
+//! @file      GUI/Model/Fit/FitParameterModel.cpp
 //! @brief     Implements class FitParameterAbsModel
 //!
 //! @homepage  http://www.bornagainproject.org
 //! @license   GNU General Public License v3 or higher (see COPYING)
-//! @copyright Forschungszentrum Jülich GmbH 2018
+//! @copyright Forschungszentrum Jülich GmbH 2021
 //! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
 //
 //  ************************************************************************************************
 
-#include "GUI/Model/Fit/FitParameterProxyModel.h"
+#include "GUI/Model/Fit/FitParameterModel.h"
 #include "GUI/Model/Fit/FitParameterContainerItem.h"
 #include "GUI/Model/Fit/FitParameterHelper.h"
 #include "GUI/Model/Fit/FitParameterItem.h"
@@ -32,8 +32,7 @@ using boost::polymorphic_downcast;
 
 using GUI::Session::ItemUtils::ParentRow;
 
-FitParameterProxyModel::FitParameterProxyModel(FitParameterContainerItem* fitParContainer,
-                                               QObject* parent)
+FitParameterModel::FitParameterModel(FitParameterContainerItem* fitParContainer, QObject* parent)
     : QAbstractItemModel(parent), m_root_item(fitParContainer)
 {
     addColumn(COL_NAME, "Name", "Name of fit parameter");
@@ -47,7 +46,7 @@ FitParameterProxyModel::FitParameterProxyModel(FitParameterContainerItem* fitPar
     m_root_item->mapper()->setOnItemDestroy(
         [this](SessionItem* parentItem) {
             if (parentItem != m_root_item) {
-                throw Error("FitParameterProxyModel::FitParameterProxyModel() -> Error. "
+                throw Error("FitParameterModel::FitParameterModel() -> Error. "
                             "Wrong item reported.");
             }
             m_root_item = nullptr;
@@ -55,13 +54,13 @@ FitParameterProxyModel::FitParameterProxyModel(FitParameterContainerItem* fitPar
         this);
 }
 
-FitParameterProxyModel::~FitParameterProxyModel()
+FitParameterModel::~FitParameterModel()
 {
     if (m_root_item)
         m_root_item->mapper()->unsubscribe(this);
 }
 
-Qt::ItemFlags FitParameterProxyModel::flags(const QModelIndex& index) const
+Qt::ItemFlags FitParameterModel::flags(const QModelIndex& index) const
 {
     if (!m_root_item)
         return Qt::NoItemFlags;
@@ -90,7 +89,7 @@ Qt::ItemFlags FitParameterProxyModel::flags(const QModelIndex& index) const
     return returnVal;
 }
 
-QModelIndex FitParameterProxyModel::index(int row, int column, const QModelIndex& parent) const
+QModelIndex FitParameterModel::index(int row, int column, const QModelIndex& parent) const
 {
     if (!m_root_item || row < 0 || column < 0 || column >= columnCount(QModelIndex())
         || (parent.isValid() && parent.column() != COL_NAME))
@@ -137,7 +136,7 @@ QModelIndex FitParameterProxyModel::index(int row, int column, const QModelIndex
     return QModelIndex();
 }
 
-QModelIndex FitParameterProxyModel::parent(const QModelIndex& child) const
+QModelIndex FitParameterModel::parent(const QModelIndex& child) const
 {
     if (!m_root_item)
         return QModelIndex();
@@ -160,7 +159,7 @@ QModelIndex FitParameterProxyModel::parent(const QModelIndex& child) const
     return QModelIndex();
 }
 
-int FitParameterProxyModel::rowCount(const QModelIndex& parent) const
+int FitParameterModel::rowCount(const QModelIndex& parent) const
 {
     if (!m_root_item)
         return 0;
@@ -179,7 +178,7 @@ int FitParameterProxyModel::rowCount(const QModelIndex& parent) const
     return 0;
 }
 
-int FitParameterProxyModel::columnCount(const QModelIndex& parent) const
+int FitParameterModel::columnCount(const QModelIndex& parent) const
 {
     if (!m_root_item)
         return 0;
@@ -199,7 +198,7 @@ int FitParameterProxyModel::columnCount(const QModelIndex& parent) const
     return 0;
 }
 
-QVariant FitParameterProxyModel::data(const QModelIndex& index, int role) const
+QVariant FitParameterModel::data(const QModelIndex& index, int role) const
 {
     if (!m_root_item)
         return QVariant();
@@ -221,7 +220,7 @@ QVariant FitParameterProxyModel::data(const QModelIndex& index, int role) const
     return QVariant();
 }
 
-bool FitParameterProxyModel::setData(const QModelIndex& index, const QVariant& value, int role)
+bool FitParameterModel::setData(const QModelIndex& index, const QVariant& value, int role)
 {
     if (!m_root_item)
         return false;
@@ -238,14 +237,14 @@ bool FitParameterProxyModel::setData(const QModelIndex& index, const QVariant& v
     return false;
 }
 
-QStringList FitParameterProxyModel::mimeTypes() const
+QStringList FitParameterModel::mimeTypes() const
 {
     QStringList types;
     types << GUI::Session::XML::LinkMimeType;
     return types;
 }
 
-QMimeData* FitParameterProxyModel::mimeData(const QModelIndexList& indexes) const
+QMimeData* FitParameterModel::mimeData(const QModelIndexList& indexes) const
 {
     auto* mimeData = new QMimeData();
     QModelIndex index = indexes.first();
@@ -261,8 +260,8 @@ QMimeData* FitParameterProxyModel::mimeData(const QModelIndexList& indexes) cons
     return mimeData;
 }
 
-bool FitParameterProxyModel::canDropMimeData(const QMimeData* data, Qt::DropAction action, int row,
-                                             int column, const QModelIndex& parent) const
+bool FitParameterModel::canDropMimeData(const QMimeData* data, Qt::DropAction action, int row,
+                                        int column, const QModelIndex& parent) const
 {
     Q_UNUSED(data);
     Q_UNUSED(action);
@@ -275,8 +274,8 @@ bool FitParameterProxyModel::canDropMimeData(const QMimeData* data, Qt::DropActi
     return drop_is_possible;
 }
 
-bool FitParameterProxyModel::dropMimeData(const QMimeData* data, Qt::DropAction action, int row,
-                                          int column, const QModelIndex& parent)
+bool FitParameterModel::dropMimeData(const QMimeData* data, Qt::DropAction action, int row,
+                                     int column, const QModelIndex& parent)
 {
     Q_UNUSED(action);
     Q_UNUSED(row);
@@ -299,8 +298,7 @@ bool FitParameterProxyModel::dropMimeData(const QMimeData* data, Qt::DropAction
     return true;
 }
 
-QVariant FitParameterProxyModel::headerData(int section, Qt::Orientation orientation,
-                                            int role) const
+QVariant FitParameterModel::headerData(int section, Qt::Orientation orientation, int role) const
 {
     if (role == Qt::DisplayRole && orientation == Qt::Horizontal)
         return m_columnNames.value(section);
@@ -309,9 +307,9 @@ QVariant FitParameterProxyModel::headerData(int section, Qt::Orientation orienta
     return QVariant();
 }
 
-void FitParameterProxyModel::onSourceDataChanged(const QModelIndex& topLeft,
-                                                 const QModelIndex& bottomRight,
-                                                 const QVector<int>& roles)
+void FitParameterModel::onSourceDataChanged(const QModelIndex& topLeft,
+                                            const QModelIndex& bottomRight,
+                                            const QVector<int>& roles)
 {
     Q_UNUSED(bottomRight);
 
@@ -325,7 +323,7 @@ void FitParameterProxyModel::onSourceDataChanged(const QModelIndex& topLeft,
         emit dataChanged(itemIndex, itemIndex, roles);
 }
 
-void FitParameterProxyModel::onSourceRowsRemoved(const QModelIndex& parent, int first, int last)
+void FitParameterModel::onSourceRowsRemoved(const QModelIndex& parent, int first, int last)
 {
     Q_UNUSED(parent);
     Q_UNUSED(first);
@@ -334,7 +332,7 @@ void FitParameterProxyModel::onSourceRowsRemoved(const QModelIndex& parent, int
     endResetModel();
 }
 
-void FitParameterProxyModel::onSourceAboutToBeReset()
+void FitParameterModel::onSourceAboutToBeReset()
 {
     if (!m_root_item)
         return;
@@ -342,34 +340,34 @@ void FitParameterProxyModel::onSourceAboutToBeReset()
     endResetModel();
 }
 
-void FitParameterProxyModel::connectModel(QAbstractItemModel* sourceModel, bool isConnect) const
+void FitParameterModel::connectModel(QAbstractItemModel* sourceModel, bool isConnect) const
 {
     ASSERT(sourceModel);
     if (isConnect) {
         connect(sourceModel, &QAbstractItemModel::dataChanged, this,
-                &FitParameterProxyModel::onSourceDataChanged);
+                &FitParameterModel::onSourceDataChanged);
         connect(sourceModel, &QAbstractItemModel::rowsRemoved, this,
-                &FitParameterProxyModel::onSourceRowsRemoved);
+                &FitParameterModel::onSourceRowsRemoved);
         connect(sourceModel, &QAbstractItemModel::modelAboutToBeReset, this,
-                &FitParameterProxyModel::onSourceAboutToBeReset);
+                &FitParameterModel::onSourceAboutToBeReset);
     } else {
         disconnect(sourceModel, &QAbstractItemModel::dataChanged, this,
-                   &FitParameterProxyModel::onSourceDataChanged);
+                   &FitParameterModel::onSourceDataChanged);
         disconnect(sourceModel, &QAbstractItemModel::rowsRemoved, this,
-                   &FitParameterProxyModel::onSourceRowsRemoved);
+                   &FitParameterModel::onSourceRowsRemoved);
         disconnect(sourceModel, &QAbstractItemModel::modelAboutToBeReset, this,
-                   &FitParameterProxyModel::onSourceAboutToBeReset);
+                   &FitParameterModel::onSourceAboutToBeReset);
     }
 }
 
-void FitParameterProxyModel::addColumn(FitParameterProxyModel::EColumn id, const QString& name,
-                                       const QString& tooltip)
+void FitParameterModel::addColumn(FitParameterModel::EColumn id, const QString& name,
+                                  const QString& tooltip)
 {
     m_columnNames[id] = name;
     m_columnToolTips[id] = tooltip;
 }
 
-QModelIndex FitParameterProxyModel::indexOfItem(SessionItem* item) const
+QModelIndex FitParameterModel::indexOfItem(SessionItem* item) const
 {
     if (!m_root_item)
         return QModelIndex();
@@ -401,7 +399,7 @@ QModelIndex FitParameterProxyModel::indexOfItem(SessionItem* item) const
     return QModelIndex();
 }
 
-SessionItem* FitParameterProxyModel::itemForIndex(const QModelIndex& index) const
+SessionItem* FitParameterModel::itemForIndex(const QModelIndex& index) const
 {
     if (!m_root_item)
         return nullptr;
@@ -417,14 +415,14 @@ SessionItem* FitParameterProxyModel::itemForIndex(const QModelIndex& index) cons
     return m_root_item;
 }
 
-SessionModel* FitParameterProxyModel::sourceModel() const
+SessionModel* FitParameterModel::sourceModel() const
 {
     ASSERT(m_root_item);
     return m_root_item->model();
 }
 
 //! Returns true if given item still exists in source model
-bool FitParameterProxyModel::isValidSourceItem(SessionItem* item) const
+bool FitParameterModel::isValidSourceItem(SessionItem* item) const
 {
     if (item == m_root_item)
         return true;
diff --git a/GUI/Model/Fit/FitParameterProxyModel.h b/GUI/Model/Fit/FitParameterModel.h
similarity index 74%
rename from GUI/Model/Fit/FitParameterProxyModel.h
rename to GUI/Model/Fit/FitParameterModel.h
index fe73b86a710879d6c890a3c0962c699df1b6ef66..06e3b8b6c394ad305c49688c9141be38040f6a6e 100644
--- a/GUI/Model/Fit/FitParameterProxyModel.h
+++ b/GUI/Model/Fit/FitParameterModel.h
@@ -2,18 +2,18 @@
 //
 //  BornAgain: simulate and fit reflection and scattering
 //
-//! @file      GUI/Model/Fit/FitParameterProxyModel.h
-//! @brief     Defines class FitParameterProxyModel
+//! @file      GUI/Model/Fit/FitParameterModel.h
+//! @brief     Defines class FitParameterModel
 //!
 //! @homepage  http://www.bornagainproject.org
 //! @license   GNU General Public License v3 or higher (see COPYING)
-//! @copyright Forschungszentrum Jülich GmbH 2018
+//! @copyright Forschungszentrum Jülich GmbH 2021
 //! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
 //
 //  ************************************************************************************************
 
-#ifndef BORNAGAIN_GUI_MODEL_FIT_FITPARAMETERPROXYMODEL_H
-#define BORNAGAIN_GUI_MODEL_FIT_FITPARAMETERPROXYMODEL_H
+#ifndef BORNAGAIN_GUI_MODEL_FIT_FITPARAMETERMODEL_H
+#define BORNAGAIN_GUI_MODEL_FIT_FITPARAMETERMODEL_H
 
 #include <QAbstractItemModel>
 #include <QStringList>
@@ -22,18 +22,15 @@ class SessionModel;
 class FitParameterContainerItem;
 class SessionItem;
 
-//! The FitParameterProxyModel adapts the original JobModel to show items from FitParameterContainer
-//! in 5 column tree view.
-//! It is derived from QAbstractItemModel (and not from QAbstractProxyModel).
-
-class FitParameterProxyModel : public QAbstractItemModel {
+//! Model to show items from FitParameterContainer in 5 column tree view.
+class FitParameterModel : public QAbstractItemModel {
     Q_OBJECT
 
 public:
-    explicit FitParameterProxyModel(FitParameterContainerItem* fitParContainer,
-                                    QObject* parent = nullptr);
+    explicit FitParameterModel(FitParameterContainerItem* fitParContainer,
+                               QObject* parent = nullptr);
 
-    ~FitParameterProxyModel() override;
+    ~FitParameterModel() override;
 
     enum EColumn { COL_NAME, COL_TYPE, COL_VALUE, COL_MIN, COL_MAX, NUM_COLUMNS };
 
@@ -78,14 +75,14 @@ private:
     QMap<int, QString> m_columnToolTips;
 };
 
-inline Qt::DropActions FitParameterProxyModel::supportedDragActions() const
+inline Qt::DropActions FitParameterModel::supportedDragActions() const
 {
     return Qt::MoveAction | Qt::CopyAction;
 }
 
-inline Qt::DropActions FitParameterProxyModel::supportedDropActions() const
+inline Qt::DropActions FitParameterModel::supportedDropActions() const
 {
     return Qt::MoveAction | Qt::CopyAction;
 }
 
-#endif // BORNAGAIN_GUI_MODEL_FIT_FITPARAMETERPROXYMODEL_H
+#endif // BORNAGAIN_GUI_MODEL_FIT_FITPARAMETERMODEL_H
diff --git a/GUI/View/Fit/FitParameterWidget.cpp b/GUI/View/Fit/FitParameterWidget.cpp
index b2e72bd2e026ed01bef34e5f7f077c290a425847..6066d012e1c766780e54cfaf2f57c03200b2ae63 100644
--- a/GUI/View/Fit/FitParameterWidget.cpp
+++ b/GUI/View/Fit/FitParameterWidget.cpp
@@ -17,7 +17,7 @@
 #include "GUI/Model/Fit/FitParameterHelper.h"
 #include "GUI/Model/Fit/FitParameterItem.h"
 #include "GUI/Model/Fit/FitParameterLinkItem.h"
-#include "GUI/Model/Fit/FitParameterProxyModel.h"
+#include "GUI/Model/Fit/FitParameterModel.h"
 #include "GUI/Model/Fit/FitSuiteItem.h"
 #include "GUI/Model/Fit/ParameterTreeItems.h"
 #include "GUI/Model/Group/FilterPropertyProxy.h"
@@ -72,7 +72,7 @@ FitParameterWidget::FitParameterWidget(QWidget* parent)
 }
 
 //! Sets ParameterTuningWidget to be able to provide it with context menu and steer
-//! it behaviour in the course of fit settings or fit running
+//! its behaviour in the course of fit settings or fit running
 
 void FitParameterWidget::setParameterTuningWidget(ParameterTuningWidget* tuningWidget)
 {
@@ -248,13 +248,13 @@ void FitParameterWidget::init_fit_model()
     m_treeView->setModel(nullptr);
 
     delete m_fitParameterModel;
-    m_fitParameterModel = new FitParameterProxyModel(
-        jobItem()->fitParameterContainerItem(), jobItem()->fitParameterContainerItem()->model());
+    m_fitParameterModel = new FitParameterModel(jobItem()->fitParameterContainerItem(),
+                                                jobItem()->fitParameterContainerItem()->model());
     m_treeView->setModel(m_fitParameterModel);
 
-    connect(m_fitParameterModel, &FitParameterProxyModel::dataChanged, this,
+    connect(m_fitParameterModel, &FitParameterModel::dataChanged, this,
             &FitParameterWidget::onFitParameterModelChange);
-    connect(m_fitParameterModel, &FitParameterProxyModel::modelReset, this,
+    connect(m_fitParameterModel, &FitParameterModel::modelReset, this,
             &FitParameterWidget::onFitParameterModelChange);
 
     onFitParameterModelChange();
diff --git a/GUI/View/Fit/FitParameterWidget.h b/GUI/View/Fit/FitParameterWidget.h
index 8cf3c718640c93f43fd42ce76edc90854d1a44dd..1247be0ee064ac8743920cdd1245b38f7b7c082d 100644
--- a/GUI/View/Fit/FitParameterWidget.h
+++ b/GUI/View/Fit/FitParameterWidget.h
@@ -23,7 +23,7 @@ class ParameterTuningWidget;
 class QTreeView;
 class QAction;
 class QMenu;
-class FitParameterProxyModel;
+class FitParameterModel;
 class ParameterItem;
 class FitParameterItem;
 class FitParameterLinkItem;
@@ -79,7 +79,7 @@ private:
     QAction* m_createFitParAction;
     QAction* m_removeFromFitParAction;
     QAction* m_removeFitParAction;
-    FitParameterProxyModel* m_fitParameterModel;
+    FitParameterModel* m_fitParameterModel;
     DeleteEventFilter* m_keyboardFilter;
     OverlayLabelController* m_infoLabel;
 };
diff --git a/Tests/Unit/GUI/TestFitParameterModel.cpp b/Tests/Unit/GUI/TestFitParameterModel.cpp
index c81388e9bae930ae53b0b020b9ae56119daf0646..314d84c4a853364ed8ec551c400e931f8fd7c635 100644
--- a/Tests/Unit/GUI/TestFitParameterModel.cpp
+++ b/Tests/Unit/GUI/TestFitParameterModel.cpp
@@ -1,7 +1,7 @@
 #include "GUI/Model/Fit/FitParameterContainerItem.h"
 #include "GUI/Model/Fit/FitParameterItem.h"
 #include "GUI/Model/Fit/FitParameterLinkItem.h"
-#include "GUI/Model/Fit/FitParameterProxyModel.h"
+#include "GUI/Model/Fit/FitParameterModel.h"
 #include "GUI/Model/Fit/FitSuiteItem.h"
 #include "GUI/Model/Job/JobModel.h"
 #include "Tests/GTestWrapper/google_test.h"
@@ -14,11 +14,10 @@ TEST_F(TestFitParameterModel, InitialState)
     JobModel source;
     auto* fitSuiteItem = source.insertItem<FitSuiteItem>();
     auto* container = fitSuiteItem->createFitParametersContainer();
-    FitParameterProxyModel proxy(dynamic_cast<FitParameterContainerItem*>(container));
+    FitParameterModel proxy(dynamic_cast<FitParameterContainerItem*>(container));
 
     EXPECT_EQ(0, proxy.rowCount(QModelIndex()));
-    EXPECT_EQ(static_cast<int>(FitParameterProxyModel::NUM_COLUMNS),
-              proxy.columnCount(QModelIndex()));
+    EXPECT_EQ(static_cast<int>(FitParameterModel::NUM_COLUMNS), proxy.columnCount(QModelIndex()));
     EXPECT_EQ(container, proxy.itemForIndex(QModelIndex()));
 }
 
@@ -27,7 +26,7 @@ TEST_F(TestFitParameterModel, addFitParameter)
     JobModel source;
     auto* fitSuiteItem = source.insertItem<FitSuiteItem>();
     auto* container = fitSuiteItem->createFitParametersContainer();
-    FitParameterProxyModel proxy(dynamic_cast<FitParameterContainerItem*>(container));
+    FitParameterModel proxy(dynamic_cast<FitParameterContainerItem*>(container));
 
     // adding fit parameter
     auto* fitPar0 = source.insertItem<FitParameterItem>(container);
@@ -38,7 +37,7 @@ TEST_F(TestFitParameterModel, addFitParameter)
 
     // checking index of root
     EXPECT_EQ(1, proxy.rowCount(QModelIndex()));
-    EXPECT_EQ(FitParameterProxyModel::NUM_COLUMNS, proxy.columnCount(QModelIndex()));
+    EXPECT_EQ(FitParameterModel::NUM_COLUMNS, proxy.columnCount(QModelIndex()));
 
     // accessing item at col=0 (original FitParameterItem)
     QModelIndex index = proxy.index(0, 0, QModelIndex());
@@ -52,9 +51,9 @@ TEST_F(TestFitParameterModel, addFitParameter)
     EXPECT_EQ(index, proxy.indexOfItem(fitPar0));
 
     // accessing item at col=2
-    index = proxy.index(0, FitParameterProxyModel::COL_MIN, QModelIndex());
+    index = proxy.index(0, FitParameterModel::COL_MIN, QModelIndex());
     EXPECT_EQ(index.row(), 0);
-    EXPECT_EQ(index.column(), FitParameterProxyModel::COL_MIN);
+    EXPECT_EQ(index.column(), FitParameterModel::COL_MIN);
     EXPECT_EQ(proxy.rowCount(index), 0);
     EXPECT_EQ(proxy.columnCount(index), 0);
 
@@ -63,9 +62,9 @@ TEST_F(TestFitParameterModel, addFitParameter)
     EXPECT_EQ(index, proxy.indexOfItem(fitPar0->minimumItem()));
 
     // accessing item at col=3
-    index = proxy.index(0, FitParameterProxyModel::COL_VALUE, QModelIndex());
+    index = proxy.index(0, FitParameterModel::COL_VALUE, QModelIndex());
     EXPECT_EQ(index.row(), 0);
-    EXPECT_EQ(index.column(), FitParameterProxyModel::COL_VALUE);
+    EXPECT_EQ(index.column(), FitParameterModel::COL_VALUE);
     EXPECT_EQ(proxy.rowCount(index), 0);
     EXPECT_EQ(proxy.columnCount(index), 0);
 
@@ -74,9 +73,9 @@ TEST_F(TestFitParameterModel, addFitParameter)
     EXPECT_EQ(index, proxy.indexOfItem(fitPar0->startValueItem()));
 
     // accessing item at col=4
-    index = proxy.index(0, FitParameterProxyModel::COL_MAX, QModelIndex());
+    index = proxy.index(0, FitParameterModel::COL_MAX, QModelIndex());
     EXPECT_EQ(index.row(), 0);
-    EXPECT_EQ(index.column(), FitParameterProxyModel::COL_MAX);
+    EXPECT_EQ(index.column(), FitParameterModel::COL_MAX);
     EXPECT_EQ(proxy.rowCount(index), 0);
     EXPECT_EQ(proxy.columnCount(index), 0);
 
@@ -95,12 +94,12 @@ TEST_F(TestFitParameterModel, addFitParameter)
 
     // checking index of root
     EXPECT_EQ(2, proxy.rowCount(QModelIndex()));
-    EXPECT_EQ(FitParameterProxyModel::NUM_COLUMNS, proxy.columnCount(QModelIndex()));
+    EXPECT_EQ(FitParameterModel::NUM_COLUMNS, proxy.columnCount(QModelIndex()));
 
     // accessing item at col=3 for fitPar0
-    index = proxy.index(0, FitParameterProxyModel::COL_VALUE, QModelIndex());
+    index = proxy.index(0, FitParameterModel::COL_VALUE, QModelIndex());
     EXPECT_EQ(index.row(), 0);
-    EXPECT_EQ(index.column(), FitParameterProxyModel::COL_VALUE);
+    EXPECT_EQ(index.column(), FitParameterModel::COL_VALUE);
     EXPECT_EQ(proxy.rowCount(index), 0);
     EXPECT_EQ(proxy.columnCount(index), 0);
 
@@ -109,9 +108,9 @@ TEST_F(TestFitParameterModel, addFitParameter)
     EXPECT_EQ(index, proxy.indexOfItem(fitPar0->startValueItem()));
 
     // accessing item at col=3 for fitPar1
-    index = proxy.index(1, FitParameterProxyModel::COL_VALUE, QModelIndex());
+    index = proxy.index(1, FitParameterModel::COL_VALUE, QModelIndex());
     EXPECT_EQ(index.row(), 1);
-    EXPECT_EQ(index.column(), FitParameterProxyModel::COL_VALUE);
+    EXPECT_EQ(index.column(), FitParameterModel::COL_VALUE);
     EXPECT_EQ(proxy.rowCount(index), 0);
     EXPECT_EQ(proxy.columnCount(index), 0);
 
@@ -125,7 +124,7 @@ TEST_F(TestFitParameterModel, addFitParameterAndLink)
     JobModel source;
     auto* fitSuiteItem = source.insertItem<FitSuiteItem>();
     auto* container = fitSuiteItem->createFitParametersContainer();
-    FitParameterProxyModel proxy(dynamic_cast<FitParameterContainerItem*>(container));
+    FitParameterModel proxy(dynamic_cast<FitParameterContainerItem*>(container));
 
     // adding fit parameter
     auto* fitPar0 = source.insertItem<FitParameterItem>(container);
@@ -140,7 +139,7 @@ TEST_F(TestFitParameterModel, addFitParameterAndLink)
 
     // checking index of root
     EXPECT_EQ(1, proxy.rowCount(QModelIndex()));
-    EXPECT_EQ(FitParameterProxyModel::NUM_COLUMNS, proxy.columnCount(QModelIndex()));
+    EXPECT_EQ(FitParameterModel::NUM_COLUMNS, proxy.columnCount(QModelIndex()));
 
     // accessing item at col=0 (original FitParameterItem)
     QModelIndex index = proxy.index(0, 0, QModelIndex());
@@ -186,7 +185,7 @@ TEST_F(TestFitParameterModel, addTwoFitParameterAndLinks)
     JobModel source;
     auto* fitSuiteItem = source.insertItem<FitSuiteItem>();
     auto* container = fitSuiteItem->createFitParametersContainer();
-    FitParameterProxyModel proxy(dynamic_cast<FitParameterContainerItem*>(container));
+    FitParameterModel proxy(dynamic_cast<FitParameterContainerItem*>(container));
 
     // adding fit parameters
     auto* fitPar0 = source.insertItem<FitParameterItem>(container);
@@ -199,7 +198,7 @@ TEST_F(TestFitParameterModel, addTwoFitParameterAndLinks)
 
     // checking index of root
     EXPECT_EQ(2, proxy.rowCount(QModelIndex()));
-    EXPECT_EQ(FitParameterProxyModel::NUM_COLUMNS, proxy.columnCount(QModelIndex()));
+    EXPECT_EQ(FitParameterModel::NUM_COLUMNS, proxy.columnCount(QModelIndex()));
 
     // accessing fitPar1
     QModelIndex index1 = proxy.index(1, 0, QModelIndex());