Add short aliases for all estimators

diff_diff/__init__.py

@@ -159,6 +159,20 @@
     load_mpdta,
 )
 
+# Estimator aliases — short names for convenience
+DiD = DifferenceInDifferences
+TWFE = TwoWayFixedEffects
+EventStudy = MultiPeriodDiD
+SDiD = SyntheticDiD
+CS = CallawaySantAnna
+CDiD = ContinuousDiD
+SA = SunAbraham
+BJS = ImputationDiD
+Gardner = TwoStageDiD
+DDD = TripleDifference
+Stacked = StackedDiD
+Bacon = BaconDecomposition
+
 __version__ = "2.6.0"
 __all__ = [
     # Estimators
@@ -174,6 +188,19 @@
     "TripleDifference",
     "TROP",
     "StackedDiD",
+    # Estimator aliases (short names)
+    "DiD",
+    "TWFE",
+    "EventStudy",
+    "SDiD",
+    "CS",
+    "CDiD",
+    "SA",
+    "BJS",
+    "Gardner",
+    "DDD",
+    "Stacked",
+    "Bacon",
     # Bacon Decomposition
     "BaconDecomposition",
     "BaconDecompositionResults",

docs/api/estimators.rst

@@ -17,6 +17,12 @@ for backward compatibility, so you can import any of them using:
 
     from diff_diff import DifferenceInDifferences, TwoWayFixedEffects, MultiPeriodDiD, SyntheticDiD
 
+Most estimators have short aliases (``TROP`` already uses its short canonical name):
+
+.. code-block:: python
+
+    from diff_diff import DiD, TWFE, EventStudy, SDiD, CS, CDiD, SA, BJS, Gardner, DDD, Stacked, Bacon
+
 .. module:: diff_diff.estimators
 
 DifferenceInDifferences

docs/quickstart.rst

@@ -22,6 +22,9 @@ The simplest DiD design has two groups (treated/control) and two periods (pre/po
    import pandas as pd
    from diff_diff import DifferenceInDifferences, generate_did_data
 
+   # Tip: most estimators have short aliases, e.g. DiD, TWFE, CS, DDD
+   # from diff_diff import DiD
+
    # Generate synthetic data with a known treatment effect
    data = generate_did_data(
        n_units=100,

tests/test_aliases.py

@@ -0,0 +1,35 @@
+"""Tests for estimator short aliases."""
+
+import diff_diff
+
+
+def test_alias_identity():
+    """Each alias is the same class object as the full name."""
+    assert diff_diff.DiD is diff_diff.DifferenceInDifferences
+    assert diff_diff.TWFE is diff_diff.TwoWayFixedEffects
+    assert diff_diff.EventStudy is diff_diff.MultiPeriodDiD
+    assert diff_diff.SDiD is diff_diff.SyntheticDiD
+    assert diff_diff.CS is diff_diff.CallawaySantAnna
+    assert diff_diff.CDiD is diff_diff.ContinuousDiD
+    assert diff_diff.SA is diff_diff.SunAbraham
+    assert diff_diff.BJS is diff_diff.ImputationDiD
+    assert diff_diff.Gardner is diff_diff.TwoStageDiD
+    assert diff_diff.DDD is diff_diff.TripleDifference
+    assert diff_diff.Stacked is diff_diff.StackedDiD
+    assert diff_diff.Bacon is diff_diff.BaconDecomposition
+
+
+def test_aliases_in_all():
+    """All aliases are listed in __all__."""
+    aliases = [
+        "DiD", "TWFE", "EventStudy", "SDiD", "CS", "CDiD",
+        "SA", "BJS", "Gardner", "DDD", "Stacked", "Bacon",
+    ]
+    for alias in aliases:
+        assert alias in diff_diff.__all__, f"{alias} missing from __all__"
+
+
+def test_alias_instantiation():
+    """Instantiating via alias produces the correct type."""
+    model = diff_diff.DiD()
+    assert isinstance(model, diff_diff.DifferenceInDifferences)