typo

arviz/data/io_pymc3.py

@@ -139,7 +139,7 @@ def find_observations(self) -> Tuple[Optional[Dict[str, Var]], Optional[Dict[str
         multi_observations = {}
         for obs in self.model.observed_RVs:
             if hasattr(obs, "observations"):
-                observations[obs.name] = obs.observation
+                observations[obs.name] = obs.observations
             elif hasattr(obs, "data"):
                 for key, val in obs.data.items():
                     multi_observations[key] = val