@@ -1266,7 +1266,8 @@ def _compute_conf_interval(data, med, iqr, bootstrap):
     if labels is None:
         labels = itertools.repeat(None)
     elif len(labels) != ncols:
-        raise ValueError("Dimensions of labels and X must be compatible")
+        raise ValueError(f"The number of labels ({len(labels)}) must match the"
+            f" number of columns ({ncols}).")
 
     input_whis = whis
     for ii, (x, label) in enumerate(zip(X, labels)):