diff --git a/pyomo/contrib/doe/doe.py b/pyomo/contrib/doe/doe.py
index 0330c38b973..12599de7c60 100644
--- a/pyomo/contrib/doe/doe.py
+++ b/pyomo/contrib/doe/doe.py
@@ -551,6 +551,9 @@ def _sequential_FIM(self, model=None):
                     "Model from experiment did not solve appropriately. Make sure the model is well-posed."
                 )
 
+            # Reset value of parameter to default value before computing finite difference perturbation
+            param.set_value(model.unknown_parameters[param])
+
             # Extract the measurement values for the scenario and append
             measurement_vals.append(
                 [pyo.value(k) for k, v in model.experiment_outputs.items()]
@@ -2140,7 +2143,7 @@ def get_unknown_parameter_values(self, model=None):
         if not hasattr(model, "unknown_parameters"):
             if not hasattr(model, "scenario_blocks"):
                 raise RuntimeError(
-                    "Model provided does not have expected structure. Please make sure model is built properly before calling `get_experiment_input_values`"
+                    "Model provided does not have expected structure. Please make sure model is built properly before calling `get_unknown_parameter_values`"
                 )
 
             theta_vals = [
@@ -2174,15 +2177,15 @@ def get_experiment_output_values(self, model=None):
         if not hasattr(model, "experiment_outputs"):
             if not hasattr(model, "scenario_blocks"):
                 raise RuntimeError(
-                    "Model provided does not have expected structure. Please make sure model is built properly before calling `get_experiment_input_values`"
+                    "Model provided does not have expected structure. Please make sure model is built properly before calling `get_experiment_output_values`"
                 )
 
             y_hat_vals = [
                 pyo.value(k)
-                for k, v in model.scenario_blocks[0].measurement_error.items()
+                for k, v in model.scenario_blocks[0].experiment_outputs.items()
             ]
         else:
-            y_hat_vals = [pyo.value(k) for k, v in model.measurement_error.items()]
+            y_hat_vals = [pyo.value(k) for k, v in model.experiment_outputs.items()]
 
         return y_hat_vals
 
@@ -2210,7 +2213,7 @@ def get_measurement_error_values(self, model=None):
         if not hasattr(model, "measurement_error"):
             if not hasattr(model, "scenario_blocks"):
                 raise RuntimeError(
-                    "Model provided does not have expected structure. Please make sure model is built properly before calling `get_experiment_input_values`"
+                    "Model provided does not have expected structure. Please make sure model is built properly before calling `get_measurement_error_values`"
                 )
 
             sigma_vals = [
diff --git a/pyomo/contrib/doe/tests/test_doe_errors.py b/pyomo/contrib/doe/tests/test_doe_errors.py
index af1e6e6cafd..611cc7c31e9 100644
--- a/pyomo/contrib/doe/tests/test_doe_errors.py
+++ b/pyomo/contrib/doe/tests/test_doe_errors.py
@@ -498,7 +498,7 @@ def test_reactor_check_get_exp_outputs_without_model(self):
 
         with self.assertRaisesRegex(
             RuntimeError,
-            "Model provided does not have expected structure. Please make sure model is built properly before calling `get_experiment_input_values`",
+            "Model provided does not have expected structure. Please make sure model is built properly before calling `get_experiment_output_values`",
         ):
             doe_obj.get_experiment_output_values()
 
@@ -517,7 +517,7 @@ def test_reactor_check_get_unknown_params_without_model(self):
 
         with self.assertRaisesRegex(
             RuntimeError,
-            "Model provided does not have expected structure. Please make sure model is built properly before calling `get_experiment_input_values`",
+            "Model provided does not have expected structure. Please make sure model is built properly before calling `get_unknown_parameter_values`",
         ):
             doe_obj.get_unknown_parameter_values()
 
@@ -536,7 +536,7 @@ def test_reactor_check_get_meas_error_without_model(self):
 
         with self.assertRaisesRegex(
             RuntimeError,
-            "Model provided does not have expected structure. Please make sure model is built properly before calling `get_experiment_input_values`",
+            "Model provided does not have expected structure. Please make sure model is built properly before calling `get_measurement_error_values`",
         ):
             doe_obj.get_measurement_error_values()
 
diff --git a/pyomo/contrib/parmest/parmest.py b/pyomo/contrib/parmest/parmest.py
index ea4a9e0e943..ea9dfc00640 100644
--- a/pyomo/contrib/parmest/parmest.py
+++ b/pyomo/contrib/parmest/parmest.py
@@ -309,7 +309,10 @@ def __init__(
         for experiment in self.exp_list:
             model = experiment.get_labeled_model()
             theta_names.extend([k.name for k, v in model.unknown_parameters.items()])
-        self.estimator_theta_names = list(set(theta_names))
+        # Utilize list(dict.fromkeys(theta_names)) to preserve parameter
+        # order compared with list(set(theta_names)), which had
+        # nondeterministic ordering of parameters
+        self.estimator_theta_names = list(dict.fromkeys(theta_names))
 
         self._second_stage_cost_exp = "SecondStageCost"
         # boolean to indicate if model is initialized using a square solve