diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index fcc82a2322a232bb9b27ea9ff73116aabc6b523f..0ed5c2dcfcda51d85c228dad863138a2ac1832dc 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -18,7 +18,7 @@ build-intel:
     - export LD_LIBRARY_PATH=$I_MPI_ROOT/lib/:$I_MPI_ROOT/lib/release:$MKLROOT/lib/intel64:$INTEL_COMP_ROOT/lib/:$INTEL_COMP_ROOT/compiler/lib/intel64/:$LD_LIBRARY_PATH:$HOME/intel/oneapi/intelpython/latest/lib/:$HOME/intel/oneapi/intelpython/latest/lib/python3.7
     - export PYTHONPATH=$HOME/intel/oneapi/intelpython/latest/lib/python3.7/site-packages/:sissopp_env/lib/python3.7/site-packages/
     - export PATH=$INTEL_COMP_ROOT/bin/:$INTEL_COMP_ROOT/bin/intel64:$I_MPI_ROOT/bin:$PATH
-    - cmake -C ../cmake/toolchains/intel_param_py.cmake ../
+    - cmake -C ../cmake/toolchains/intel_param_py.cmake -DBUILD_TESTS=ON ../
     - make
     - make install
     - cd ../
@@ -105,7 +105,7 @@ build-gnu:
     - export PYTHONPATH=$HOME/intel/oneapi/intelpython/latest/lib/python3.7/site-packages/:sissopp_env/lib/python3.7/site-packages/
     - mkdir build_gcc/
     - cd build_gcc/
-    - cmake -C ../cmake/toolchains/gnu_param_py.cmake ../
+    - cmake -C ../cmake/toolchains/gnu_param_py.cmake -DBUILD_TESTS=ON ../
     - make
     - make install
     - cd ../
diff --git a/CMakeLists.txt b/CMakeLists.txt
index a7f423765350f3601bc78d5af3759287c184f268..5556a11ebcf31ec43c2c34de73100facebd670c9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,24 +21,33 @@ set(CMAKE_CXX_EXTENSIONS OFF)
 
 # compiler options
 option(EXTERNAL_BOOST "Use an external boost library" OFF)
-option(USE_PYTHON "Whether to compile with python binding support" ON)
-option(USE_PARAMS "If true use non-linear parameterization" OFF)
+option(BUILD_PYTHON "Whether to compile with python binding support" ON)
+option(BUILD_PARAMS "If true use non-linear parameterization" OFF)
+option(BUILD_TESTS "Whether to compile with python binding support" OFF)
 
-if(USE_PARAMS)
-    message(STATUS "USE_PARAMS True")
+if(BUILD_PARAMS)
+    message(STATUS "BUILD_PARAMS True")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DPARAMETERIZE")
-    set(USE_PARAMS TRUE)
-else(USE_PARAMS)
-    message(STATUS "USE_PARAMS False")
-    set(USE_PARAMS FALSE)
+    set(BUILD_PARAMS TRUE)
+else(BUILD_PARAMS)
+    message(STATUS "BUILD_PARAMS False")
+    set(BUILD_PARAMS FALSE)
 endif()
 
-if(USE_PYTHON)
-    message(STATUS "USE PYTHON True")
-    set(USE_PYTHON TRUE)
-else(USE_PYTHON)
-    message(STATUS "USE PYTHON False")
-    set(USE_PYTHON FALSE)
+if(BUILD_PYTHON)
+    message(STATUS "BUILD_PYTHON True")
+    set(BUILD_PYTHON TRUE)
+else(BUILD_PYTHON)
+    message(STATUS "BUILD_PYTHON False")
+    set(BUILD_PYTHON FALSE)
+endif()
+
+if(BUILD_TESTS)
+    message(STATUS "Building tests")
+    set(BUILD_TESTS TRUE)
+else(BUILD_TESTS)
+    message(STATUS "Not building tests")
+    set(BUILD_TESTS FALSE)
 endif()
 
 if(EXTERNAL_BOOST)
@@ -61,7 +70,7 @@ if (OPENMP_FOUND)
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
 endif(OPENMP_FOUND)
 
-if(USE_PYTHON)
+if(BUILD_PYTHON)
     # Check python  settings
     find_package(PythonInterp 3 REQUIRED)
     execute_process(
@@ -144,7 +153,7 @@ if(EXTERNAL_BOOST)
     find_package(Boost REQUIRED COMPONENTS filesystem system mpi serialization)
     set(Boost_LIBS ${Boost_LIBRARIES})
 
-    if(USE_PYTHON)
+    if(BUILD_PYTHON)
         if(${Boost_VERSION} VERSION_LESS 106700)
             find_package(Boost ${NEEDED_Boost_VERSION} REQUIRED COMPONENTS python3 numpy3)
         else()
@@ -217,7 +226,7 @@ else(EXTERNAL_BOOST)
     endif()
     message(STATUS "building boost with toolset: ${Boost_TOOLSET}")
     set(Boost_CONFIGURE_COMMAND bash ${CMAKE_CURRENT_LIST_DIR}/cmake/boost/boost_configure.sh ${Boost_INSTALL_DIR} ${Boost_TOOLSET} ${Boost_LIBRARY_DIRS})
-    if(USE_PYTHON)
+    if(BUILD_PYTHON)
         set(Boost_CONFIGURE_COMMAND ${Boost_CONFIGURE_COMMAND} ${PYTHON_VERSION} ${PYTHON_PREFIX} ${PYTHON_INCLUDE_PATH} ${PYTHON_LIBDIR})
     endif()
 
@@ -262,7 +271,7 @@ else(EXTERNAL_BOOST)
     list(APPEND Boost_LIBRARIES ${Boost_LIBRARY_DIRS}/${Boost_LIBRARY_PREFIX}boost_serialization${Boost_LIBRARY_SUFFIX})
     list(APPEND Boost_LIBRARIES ${Boost_LIBRARY_DIRS}/${Boost_LIBRARY_PREFIX}boost_system${Boost_LIBRARY_SUFFIX})
     list(APPEND Boost_LIBRARIES ${Boost_LIBRARY_DIRS}/${Boost_LIBRARY_PREFIX}boost_filesystem${Boost_LIBRARY_SUFFIX})
-    if(USE_PYTHON)
+    if(BUILD_PYTHON)
         add_library( boost::python${BOOST_PYTHON_VERSION} SHARED IMPORTED )
         set_property( TARGET boost::python${BOOST_PYTHON_VERSION} PROPERTY IMPORTED_LOCATION ${Boost_LIBRARY_DIRS}/${Boost_LIBRARY_PREFIX}boost_python${BOOST_PYTHON_VERSION}${Boost_LIBRARY_SUFFIX} )
         set_property( TARGET boost::python${BOOST_PYTHON_VERSION} PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${Boost_INCLUDE_DIRS} )
@@ -295,7 +304,7 @@ get_filename_component(LAPACK_DIR ${LAPACK_LIBRARY} DIRECTORY)
 
 message(STATUS "LAPACK_LIBRARIES = ${LAPACK_LIBRARIES}")
 
-if(USE_PYTHON)
+if(BUILD_PYTHON)
     foreach(LIB ${LAPACK_LIBRARIES})
         get_filename_component(LAPACK_FILE ${LIB} NAME)
         list(APPEND PYTHON_LAPACK_LIBRARIES  ${LAPACK_FILE})
@@ -362,25 +371,27 @@ ExternalProject_Add(
 set(COIN_CLP_LIBRARIES "${COIN_CLP_LIBRARY_DIRS}/libClp.so;${COIN_CLP_LIBRARY_DIRS}/libCoinUtils.so")
 include_directories(${COIN_CLP_INCLUDE_DIRS})
 
-find_package(GTest)
-if(NOT GTEST_FOUND)
-    set(GTEST_BUILD_DIR "${CMAKE_CURRENT_BINARY_DIR}/external/gtest/build/")
-    set(GTEST_INSTALL_DIR "${CMAKE_CURRENT_BINARY_DIR}/external/gtest/bin/")
-    set(GTEST_INCLUDE_DIRS "${GTEST_INSTALL_DIR}/include")
-    set(GTEST_LIBRARY_DIRS "${CMAKE_CURRENT_LIST_DIR}/lib/gtest/")
-
-    ExternalProject_Add(
-        external_gtest
-        PREFIX "external/gtest"
-        GIT_REPOSITORY "https://github.com/google/googletest.git"
-        GIT_TAG "v1.10.x"
-        CMAKE_ARGS "-DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER};-DCMAKE_C_COMPILER=${CMAKE_C_COMPILER};-DCMAKE_INSTALL_PREFIX=${GTEST_INSTALL_DIR};-DCMAKE_INSTALL_LIBDIR=${GTEST_LIBRARY_DIRS};-DBUILD_SHARED_LIBS=ON;"
-        BINARY_DIR "${GTEST_BUILD_DIR}"
-        INSTALL_DIR "${GTEST_INSTALL_DIR}"
-    )
-    set(GTEST_BOTH_LIBRARIES "${GTEST_LIBRARY_DIRS}/libgtest.so;${GTEST_LIBRARY_DIRS}/libgtest_main.so;${GTEST_LIBRARY_DIRS}/libgmock.so;${GTEST_LIBRARY_DIRS}/libgmock_main.so")
+if(BUILD_TESTS)
+    find_package(GTest)
+    if(NOT GTEST_FOUND)
+        set(GTEST_BUILD_DIR "${CMAKE_CURRENT_BINARY_DIR}/external/gtest/build/")
+        set(GTEST_INSTALL_DIR "${CMAKE_CURRENT_BINARY_DIR}/external/gtest/bin/")
+        set(GTEST_INCLUDE_DIRS "${GTEST_INSTALL_DIR}/include")
+        set(GTEST_LIBRARY_DIRS "${CMAKE_CURRENT_LIST_DIR}/lib/gtest/")
+
+        ExternalProject_Add(
+            external_gtest
+            PREFIX "external/gtest"
+            GIT_REPOSITORY "https://github.com/google/googletest.git"
+            GIT_TAG "v1.10.x"
+            CMAKE_ARGS "-DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER};-DCMAKE_C_COMPILER=${CMAKE_C_COMPILER};-DCMAKE_INSTALL_PREFIX=${GTEST_INSTALL_DIR};-DCMAKE_INSTALL_LIBDIR=${GTEST_LIBRARY_DIRS};-DBUILD_SHARED_LIBS=ON;"
+            BINARY_DIR "${GTEST_BUILD_DIR}"
+            INSTALL_DIR "${GTEST_INSTALL_DIR}"
+        )
+        set(GTEST_BOTH_LIBRARIES "${GTEST_LIBRARY_DIRS}/libgtest.so;${GTEST_LIBRARY_DIRS}/libgtest_main.so;${GTEST_LIBRARY_DIRS}/libgmock.so;${GTEST_LIBRARY_DIRS}/libgmock_main.so")
+    endif()
+    include_directories(${GTEST_INCLUDE_DIRS})
 endif()
-include_directories(${GTEST_INCLUDE_DIRS})
 
 set(FMT_BUILD_DIR "${CMAKE_CURRENT_BINARY_DIR}/external/fmt/build/")
 set(FMT_INSTALL_DIR "${CMAKE_CURRENT_BINARY_DIR}/external/fmt/bin/")
@@ -402,4 +413,7 @@ message(STATUS "FMT_LIBRARIES: ${FMT_LIBRARIES}")
 
 include_directories(${CMAKE_CURRENT_LIST_DIR}/src)
 add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/src)
-add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/tests/googletest/)
+
+if(BUILD_TESTS)
+    add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/tests/googletest/)
+endif()
diff --git a/README.md b/README.md
index 4f1880ef15d6784d27cedfb29ec5fbc33701811c..b2d66feeb41bb12e79fcf9db5286feb0fc166253 100644
--- a/README.md
+++ b/README.md
@@ -35,7 +35,7 @@ set(CMAKE_CXX_FLAGS "-O2" CACHE STRING "")
 #################
 # Feature Flags #
 #################
-set(USE_PYTHON ON CACHE BOOL "")
+set(BUILD_PYTHON ON CACHE BOOL "")
 set(EXTERNAL_BOOST OFF CACHE BOOL "")
 ```
 Here the `-O2` flag is for optimizations, it is recommended to stay as `-O2` or `-O3`, but it can be changed to match compiler requirements.
@@ -64,7 +64,7 @@ make install
 Once all the commands are run `sisso++` should be in the `~/cpp_sisso/main directory/bin/` directory.
 
 ### Install `_sisso`
-To install the python bindings first ensure your python path matches the path used to configure `boost` and then repeat the same commands as above but set `USE_PYTHON` in `initial_config.cmake` to `ON`.
+To install the python bindings first ensure your python path matches the path used to configure `boost` and then repeat the same commands as above but set `BUILD_PYTHON` in `initial_config.cmake` to `ON`.
 
 Once installed you should have access to the python interface via `import cpp_sisso`.
 
diff --git a/cmake/toolchains/gnu_base.cmake b/cmake/toolchains/gnu_base.cmake
index cc2df6b5ec11b5803e7ff1867ab4e5e87b8fa3d2..b99c14b3b28ef1baf7f05703441e6014e9f08f31 100644
--- a/cmake/toolchains/gnu_base.cmake
+++ b/cmake/toolchains/gnu_base.cmake
@@ -8,5 +8,5 @@ set(CMAKE_CXX_FLAGS "-O3 -march=native" CACHE STRING "")
 #################
 # Feature Flags #
 #################
-set(USE_PARAMS OFF CACHE BOOL "")
-set(USE_PYTHON OFF CACHE BOOL "")
+set(BUILD_PARAMS OFF CACHE BOOL "")
+set(BUILD_PYTHON OFF CACHE BOOL "")
diff --git a/cmake/toolchains/gnu_param.cmake b/cmake/toolchains/gnu_param.cmake
index a83410f57cdcf6e8647aca171b691e22677e41c7..5a9e4937f9dbd341a5a7d23e5866cac2bee87c5f 100644
--- a/cmake/toolchains/gnu_param.cmake
+++ b/cmake/toolchains/gnu_param.cmake
@@ -8,5 +8,5 @@ set(CMAKE_CXX_FLAGS "-O3 -march=native" CACHE STRING "")
 #################
 # Feature Flags #
 #################
-set(USE_PYTHON OFF CACHE BOOL "")
-set(USE_PARAMS ON CACHE BOOL "")
+set(BUILD_PYTHON OFF CACHE BOOL "")
+set(BUILD_PARAMS ON CACHE BOOL "")
diff --git a/cmake/toolchains/gnu_param_py.cmake b/cmake/toolchains/gnu_param_py.cmake
index 9c07e6463058e5df5bb2a655fb764be9ef14e177..4f09990cacf4d26cd445440e16474631617f46c2 100644
--- a/cmake/toolchains/gnu_param_py.cmake
+++ b/cmake/toolchains/gnu_param_py.cmake
@@ -8,5 +8,5 @@ set(CMAKE_CXX_FLAGS "-O3 -march=native" CACHE STRING "")
 #################
 # Feature Flags #
 #################
-set(USE_PYTHON ON CACHE BOOL "")
-set(USE_PARAMS ON CACHE BOOL "")
+set(BUILD_PYTHON ON CACHE BOOL "")
+set(BUILD_PARAMS ON CACHE BOOL "")
diff --git a/cmake/toolchains/gnu_py.cmake b/cmake/toolchains/gnu_py.cmake
index 38fb700dcfda2915b9c2e19289ef7cfa92b06f3e..3cf38dd59635118bb31309347797989b837f3a82 100644
--- a/cmake/toolchains/gnu_py.cmake
+++ b/cmake/toolchains/gnu_py.cmake
@@ -8,5 +8,5 @@ set(CMAKE_CXX_FLAGS "-O3 -march=native" CACHE STRING "")
 #################
 # Feature Flags #
 #################
-set(USE_PARAMS OFF CACHE BOOL "")
-set(USE_PYTHON ON CACHE BOOL "")
+set(BUILD_PARAMS OFF CACHE BOOL "")
+set(BUILD_PYTHON ON CACHE BOOL "")
diff --git a/cmake/toolchains/intel_base.cmake b/cmake/toolchains/intel_base.cmake
index 4d7336a6dd2e40c12e1dc7df03806a08403c5f84..84930b386dc8fa86848bd3b3505ab419ca830915 100644
--- a/cmake/toolchains/intel_base.cmake
+++ b/cmake/toolchains/intel_base.cmake
@@ -8,6 +8,6 @@ set(CMAKE_CXX_FLAGS "-O3 -xhost" CACHE STRING "")
 #################
 # Feature Flags #
 #################
-set(USE_PARAMS OFF CACHE BOOL "")
-set(USE_PYTHON OFF CACHE BOOL "")
+set(BUILD_PARAMS OFF CACHE BOOL "")
+set(BUILD_PYTHON OFF CACHE BOOL "")
 
diff --git a/cmake/toolchains/intel_param.cmake b/cmake/toolchains/intel_param.cmake
index 66e01cbf46fda085c43c8eab4b86c3b996e117aa..a1e5fc24064fed683c7b667fdc3c93176634255e 100644
--- a/cmake/toolchains/intel_param.cmake
+++ b/cmake/toolchains/intel_param.cmake
@@ -8,6 +8,6 @@ set(CMAKE_CXX_FLAGS "-O3 -xhost" CACHE STRING "")
 #################
 # Feature Flags #
 #################
-set(USE_PARAMS ON CACHE BOOL "")
-set(USE_PYTHON OFF CACHE BOOL "")
+set(BUILD_PARAMS ON CACHE BOOL "")
+set(BUILD_PYTHON OFF CACHE BOOL "")
 set(EXTERNAL_BOOST OFF CACHE BOOL "")
diff --git a/cmake/toolchains/intel_param_py.cmake b/cmake/toolchains/intel_param_py.cmake
index 3b88a27cba789fef2ef0d555e9fdb71221f57d74..07a20b7281e51dd7e377383ea5b2adb14f8e5a10 100644
--- a/cmake/toolchains/intel_param_py.cmake
+++ b/cmake/toolchains/intel_param_py.cmake
@@ -8,6 +8,6 @@ set(CMAKE_CXX_FLAGS "-O3 -xhost" CACHE STRING "")
 #################
 # Feature Flags #
 #################
-set(USE_PARAMS ON CACHE BOOL "")
-set(USE_PYTHON ON CACHE BOOL "")
+set(BUILD_PARAMS ON CACHE BOOL "")
+set(BUILD_PYTHON ON CACHE BOOL "")
 
diff --git a/cmake/toolchains/intel_py.cmake b/cmake/toolchains/intel_py.cmake
index 419538c4975326ee9a0d09b1c07c2dde157f3856..36932d7deeccabca4abb9973d5d52ae7aa22baea 100644
--- a/cmake/toolchains/intel_py.cmake
+++ b/cmake/toolchains/intel_py.cmake
@@ -8,6 +8,6 @@ set(CMAKE_CXX_FLAGS "-O3 -xhost" CACHE STRING "")
 #################
 # Feature Flags #
 #################
-set(USE_PARAMS OFF CACHE BOOL "")
-set(USE_PYTHON ON CACHE BOOL "")
+set(BUILD_PARAMS OFF CACHE BOOL "")
+set(BUILD_PYTHON ON CACHE BOOL "")
 set(EXTERNAL_BOOST OFF CACHE BOOL "")
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 28ba57bfeb4c5534e6b291b27b07e2dbcaf5e696..9e10ecf9cb9c765641069c666ec00d819d48c41f 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -11,7 +11,7 @@ file(GLOB_RECURSE NOT_SISSOPP_SOURCES python/*.cpp)
 list(REMOVE_ITEM SISSOPP_SOURCES ${NOT_SISSOPP_SOURCES})
 list(REMOVE_ITEM SISSOPP_SOURCES ${CMAKE_CURRENT_LIST_DIR}/main.cpp)
 
-if(NOT USE_PARAMS)
+if(NOT BUILD_PARAMS)
     file(GLOB_RECURSE NOT_SISSOPP_SOURCES */parameterize*.cpp)
     list(REMOVE_ITEM SISSOPP_SOURCES ${NOT_SISSOPP_SOURCES})
 
@@ -47,7 +47,7 @@ set_target_properties(sisso++
 target_link_libraries(sisso++ libsisso ${LAPACK_LIBRARIES} ${MPI_LIBRARIES} -Wl,--rpath=${Boost_LIB_DIR} -Wl,--rpath=${LAPACK_DIR} ${Boost_LIBRARIES} ${COIN_CLP_LIBRARIES} ${NLOPT_LIBRARIES} ${OPENMP_LIBRARIES} ${FMT_LIBRARIES})
 install(TARGETS sisso++ DESTINATION ${CMAKE_CURRENT_LIST_DIR}/../bin/)
 
-if(USE_PYTHON)
+if(BUILD_PYTHON)
     include(${CMAKE_CURRENT_LIST_DIR}/../cmake/TransferDocStrings.cmake)
     set(CMAKE_INSTALL_RPATH ${PYTHON_PREFIX}/lib/;${Boost_LIBRARY_DIRS};${LAPACK_DIR};${MPI_DIR};${COIN_CLP_LIBRARY_DIRS};${NLOPT_LIBRARY_DIRS};${COIN_UTILS_LIBRARY_DIRS};${CMAKE_CURRENT_LIST_DIR}/../lib/;${PYTHON_INSTDIR}/cpp_sisso/;${FMT_LIBRARY_DIRS})
 
@@ -57,7 +57,7 @@ if(USE_PYTHON)
     file(GLOB_RECURSE SISSOLIB_SOURCES ${CMAKE_CURRENT_LIST_DIR}/python/*cpp)
     list(REMOVE_ITEM SISSOLIB_SOURCES ${CMAKE_CURRENT_LIST_DIR}/main.cpp)
     list(REMOVE_ITEM SISSOLIB_SOURCES ${CMAKE_CURRENT_LIST_DIR}/python/bindings_docstring_keyed.cpp)
-    if(NOT USE_PARAMS)
+    if(NOT BUILD_PARAMS)
         file(GLOB_RECURSE NOT_SISSOLIB_SOURCES */parameterize*.cpp)
         list(REMOVE_ITEM SISSOLIB_SOURCES ${NOT_SISSOLIB_SOURCES})
         list(REMOVE_ITEM SISSOLIB_SOURCES ${CMAKE_CURRENT_LIST_DIR}/feature_creation/node/operator_nodes/allowed_parameter_ops.cpp)
@@ -99,7 +99,7 @@ endif()
 
 if(NOT EXTERNAL_BOOST)
     add_dependencies(sisso++ external_boost)
-    if(USE_PYTHON)
+    if(BUILD_PYTHON)
         add_dependencies(_sisso external_boost)
     endif()
 endif()
diff --git a/tests/googletest/CMakeLists.txt b/tests/googletest/CMakeLists.txt
index a1675e225c43a6c63b76ba6e93154379cbe169c7..5f9bde1bab30bd1e4d2215421927130b8c6274db 100644
--- a/tests/googletest/CMakeLists.txt
+++ b/tests/googletest/CMakeLists.txt
@@ -1,7 +1,7 @@
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-deprecated-declarations")
 set(CMAKE_INSTALL_RPATH ${Boost_LIBRARY_DIRS};${LAPACK_DIR};${MPI_DIR};${COIN_CLP_LIBRARY_DIRS};${COIN_UTILS_LIBRARY_DIRS};${GTEST_LIBRARY_DIRS};${NLOPT_LIBRARY_DIRS};${FMT_LIBRARY_DIRS};${CMAKE_CURRENT_LIST_DIR}/../../lib/)
 
-file(GLOB_RECURSE SISSO_TEST_SOURCES *.cc)
+file(GLOB_RECURSE SISSO_TEST_SOURCES feature_creation/*.cc)
 add_executable(sisso_test  ${SISSO_TEST_SOURCES})
 
 set_target_properties(sisso_test