Bump version to 1.2.0

New in v1.2.0:
- Pre-Trends Power Analysis (Roth 2022)
  - PreTrendsPower class with MDV and power curve computation
  - compute_pretrends_power() and compute_mdv() convenience functions
  - plot_pretrends_power() visualization
  - Integration with Honest DiD
  - Tutorial and API documentation

See CHANGELOG.md for full details.

Author: claude

CHANGELOG.md

@@ -5,6 +5,25 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.2.0] - 2026-01-07
+
+### Added
+- **Pre-Trends Power Analysis** (Roth 2022) for assessing informativeness of pre-trends tests
+  - `PreTrendsPower` class for computing power and minimum detectable violation (MDV)
+  - `PreTrendsPowerResults` dataclass with power, MDV, and test statistics
+  - `PreTrendsPowerCurve` for power curves across violation magnitudes
+  - `compute_pretrends_power()` and `compute_mdv()` convenience functions
+  - Multiple violation types: `linear`, `constant`, `last_period`, `custom`
+  - Integration with Honest DiD via `sensitivity_to_honest_did()` method
+  - `plot_pretrends_power()` visualization for power curves
+  - Tutorial notebook: `docs/tutorials/07_pretrends_power.ipynb`
+  - Full API documentation: `docs/api/pretrends.rst`
+
+**Reference**: Roth, J. (2022). "Pretest with Caution: Event-Study Estimates after Testing for Parallel Trends." *American Economic Review: Insights*, 4(3), 305-322.
+
+### Fixed
+- **Reference period handling in pre-trends analysis**: Fixed bug where reference period was incorrectly assigned `avg_se` instead of being excluded from power calculations. Now properly excludes the omitted reference period from the joint Wald test.
+
 ## [1.1.1] - 2026-01-06
 
 ### Fixed
@@ -215,6 +234,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - `to_dict()` and `to_dataframe()` export methods
   - `is_significant` and `significance_stars` properties
 
+[1.2.0]: https://github.com/igerber/diff-diff/compare/v1.1.1...v1.2.0
+[1.1.1]: https://github.com/igerber/diff-diff/compare/v1.1.0...v1.1.1
 [1.1.0]: https://github.com/igerber/diff-diff/compare/v1.0.2...v1.1.0
 [1.0.2]: https://github.com/igerber/diff-diff/compare/v1.0.1...v1.0.2
 [1.0.1]: https://github.com/igerber/diff-diff/compare/v1.0.0...v1.0.1

diff_diff/__init__.py

@@ -98,7 +98,7 @@
     plot_sensitivity,
 )
 
-__version__ = "1.1.1"
+__version__ = "1.2.0"
 __all__ = [
     # Estimators
     "DifferenceInDifferences",

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "diff-diff"
-version = "1.1.1"
+version = "1.2.0"
 description = "A library for Difference-in-Differences causal inference analysis"
 readme = "README.md"
 license = "MIT"