diff --git a/pyproject.toml b/pyproject.toml
index 709e5f3..56a983d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -7,6 +7,10 @@ requires = [
 ]
 build-backend = "setuptools.build_meta"
 
+[tool.cibuildwheel]
+test-requires = "pytest"
+test-command = "pytest {project}/tests"
+
 [project]
 dependencies=["numpy >= 1.24.1",
               "pandas >= 1.5.3",
@@ -28,4 +32,4 @@ dynamic = ["version"]
 
 [tool.setuptools_scm]
 # https://github.com/pypa/setuptools_scm/issues/342
-local_scheme = "no-local-version" 
\ No newline at end of file
+local_scheme = "no-local-version"
\ No newline at end of file
diff --git a/src/mssm/src/python/formula.py b/src/mssm/src/python/formula.py
index f3a3a36..f191298 100644
--- a/src/mssm/src/python/formula.py
+++ b/src/mssm/src/python/formula.py
@@ -35,7 +35,7 @@ def map_csc_to_eigen(X):
    see: https://github.com/fwilliams/numpyeigen/blob/master/src/npe_sparse_array.h#L74
    """
 
-   if X.getformat() != "csc":
+   if X.format != "csc":
       raise TypeError(f"Format of sparse matrix passed to c++ MUST be 'csc' but is {X.getformat()}")
 
    rows, cols = X.shape
diff --git a/tests/test_gamm.py b/tests/test_gamm.py
new file mode 100644
index 0000000..c9ffa62
--- /dev/null
+++ b/tests/test_gamm.py
@@ -0,0 +1,73 @@
+from mssm.models import *
+import numpy as np
+
+class Test_GAM:
+
+    dat = pd.read_csv("./tutorials/data/GAMM/sim_dat.csv")
+
+    # mssm requires that the data-type for variables used as factors is 'O'=object
+    dat = dat.astype({'series': 'O',
+                    'cond':'O',
+                    'sub':'O',
+                    'series':'O'})
+    
+    formula = Formula(lhs=lhs("y"), # The dependent variable - here y!
+                        terms=[i(), # The intercept, a
+                               f(["time"])], # The f(time) term, by default parameterized with 9 basis functions (after absorbing one for identifiability)
+                        data=dat,
+                        print_warn=False)
+        
+    model = GAMM(formula,Gaussian())
+
+    model.fit()
+
+    def test_GAMedf(self):
+        assert round(self.model.edf,ndigits=3) == 9.723
+
+    def test_GAMTermEdf(self):
+        assert round(self.model.term_edf[0],ndigits=3) == 8.723
+    
+    def test_GAMsigma(self):
+        _, sigma = self.model.get_pars()
+        assert round(sigma,ndigits=3) == 1084.879
+    
+    def test_GAMlam(self):
+        assert round(self.model.formula.penalties[0].lam,ndigits=5) == 0.0089
+
+
+class Test_GAMM:
+
+    dat = pd.read_csv("./tutorials/data/GAMM/sim_dat.csv")
+
+    # mssm requires that the data-type for variables used as factors is 'O'=object
+    dat = dat.astype({'series': 'O',
+                    'cond':'O',
+                    'sub':'O',
+                    'series':'O'})
+    
+    formula = Formula(lhs=lhs("y"), # The dependent variable - here y!
+                      terms=[i(), # The intercept, a
+                               l(["cond"]), # For cond='b'
+                               f(["time"],by="cond",constraint=ConstType.QR), # to-way interaction between time and cond; one smooth over time per cond level
+                               f(["x"],by="cond",constraint=ConstType.QR), # to-way interaction between x and cond; one smooth over x per cond level
+                               f(["time","x"],by="cond",constraint=ConstType.QR), # three-way interaction
+                               fs(["time"],rf="sub")], # Random non-linear effect of time - one smooth per level of factor sub
+                        data=dat,
+                        print_warn=False)
+        
+    model = GAMM(formula,Gaussian())
+
+    model.fit()
+
+    def test_GAMMedf(self):
+        assert round(self.model.edf,ndigits=3) == 153.601
+
+    def test_GAMMTermEdf(self):
+        assert np.array_equal(np.round(self.model.term_edf,decimals=3),np.array([6.892, 8.635, 1.181, 1.001, 1.001, 1.029, 131.861])) == True
+    
+    def test_GAMMsigma(self):
+        _, sigma = self.model.get_pars()
+        assert round(sigma,ndigits=3) == 577.196
+    
+    def test_GAMMlam(self):
+        assert np.array_equal(np.round([p.lam for p in self.model.formula.penalties],decimals=3),np.array([0.004, 0.006, 5842.507, 1101786.56 , 328846.811, 174267.629, 162215.095, 1178.787, 0.119, 2.166])) == True
\ No newline at end of file
diff --git a/tutorials/1) GAMMs.ipynb b/tutorials/1) GAMMs.ipynb
index d51e3de..143d181 100644
--- a/tutorials/1) GAMMs.ipynb	
+++ b/tutorials/1) GAMMs.ipynb	
@@ -312,6 +312,26 @@
     "y = model.formula.y_flat[model.formula.NOT_NA_flat] # The dependent variable after NAs were removed"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": 15,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "0.0089"
+      ]
+     },
+     "execution_count": 15,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "round(model.formula.penalties[0].lam,ndigits=5)"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 11,
@@ -1248,9 +1268,18 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 36,
+   "execution_count": 16,
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stderr",
+     "output_type": "stream",
+     "text": [
+      "/Users/joshmac/Documents/repos/mssm/src/mssm/src/python/formula.py:1106: UserWarning: 3003 y values (9.32%) are NA.\n",
+      "  warnings.warn(f\"{data.shape[0] - data[NAs_flat].shape[0]} {self.get_lhs().variable} values ({round((data.shape[0] - data[NAs_flat].shape[0]) / data.shape[0] * 100,ndigits=2)}%) are NA.\")\n"
+     ]
+    }
+   ],
    "source": [
     "formula7 = Formula(lhs=lhs(\"y\"), # The dependent variable - here y!\n",
     "                        terms=[i(), # The intercept, a\n",
@@ -1264,7 +1293,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 37,
+   "execution_count": 17,
    "metadata": {},
    "outputs": [
     {
@@ -1278,7 +1307,7 @@
      "name": "stderr",
      "output_type": "stream",
      "text": [
-      "Converged!:  38%|███▊      | 19/50 [00:07<00:12,  2.55it/s]                "
+      "Converged!:  38%|███▊      | 19/50 [00:06<00:10,  2.87it/s]                "
      ]
     },
     {