igerber · igerber · Mar 18, 2026 · Mar 18, 2026 · Mar 18, 2026 · Mar 18, 2026
diff --git a/.readthedocs.yaml b/.readthedocs.yaml
@@ -5,6 +5,8 @@ version: 2
 
 build:
   os: ubuntu-22.04
+  apt_packages:
+    - pandoc
   tools:
     python: "3.11"
   jobs:
@@ -16,7 +18,7 @@ build:
       #
       # Keep in sync with pyproject.toml [project.dependencies]
       # and [project.optional-dependencies.docs].
-      - pip install "numpy>=1.20.0" "pandas>=1.3.0" "scipy>=1.7.0" "sphinx>=6.0" "sphinx-rtd-theme>=1.0"
+      - pip install "numpy>=1.20.0" "pandas>=1.3.0" "scipy>=1.7.0" "sphinx>=6.0" "pydata-sphinx-theme>=0.15" "sphinxext-opengraph>=0.9" "sphinx-sitemap>=2.5" "nbsphinx>=0.9" "matplotlib>=3.5"
 
 # Build documentation in the "docs/" directory with Sphinx
 sphinx:

diff --git a/CITATION.cff b/CITATION.cff
@@ -0,0 +1,27 @@
+cff-version: 1.2.0
+title: "diff-diff: Difference-in-Differences Causal Inference for Python"
+message: "If you use this software, please cite it as below."
+type: software
+authors:
+  - name: "diff-diff contributors"
+license: MIT
+version: "2.7.1"
+date-released: "2026-03-18"
+url: "https://github.com/igerber/diff-diff"
+repository-code: "https://github.com/igerber/diff-diff"
+keywords:
+  - difference-in-differences
+  - causal-inference
+  - econometrics
+  - python
+  - treatment-effects
+  - event-study
+  - staggered-adoption
+  - parallel-trends
+  - synthetic-control
+  - panel-data
+abstract: >-
+  A Python library for Difference-in-Differences (DiD) causal inference analysis.
+  Provides sklearn-like estimators for modern DiD methods including
+  Callaway-Sant'Anna, Synthetic DiD, Honest DiD, event studies, and parallel
+  trends testing. Validated against R packages (did, synthdid, fixest).
diff --git a/README.md b/README.md
@@ -1,5 +1,11 @@
 # diff-diff
 
+[![PyPI version](https://img.shields.io/pypi/v/diff-diff.svg)](https://pypi.org/project/diff-diff/)
+[![Python versions](https://img.shields.io/pypi/pyversions/diff-diff.svg)](https://pypi.org/project/diff-diff/)
+[![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)
+[![Downloads](https://img.shields.io/pypi/dm/diff-diff.svg)](https://pypi.org/project/diff-diff/)
+[![Documentation](https://readthedocs.org/projects/diff-diff/badge/?version=stable)](https://diff-diff.readthedocs.io/en/stable/)
+
 A Python library for Difference-in-Differences (DiD) causal inference analysis with an sklearn-like API and statsmodels-style outputs.
 
 ## Installation
@@ -2909,6 +2915,21 @@ The `HonestDiD` module implements sensitivity analysis methods for relaxing the
 
 - **Cunningham, S. (2021).** *Causal Inference: The Mixtape*. Yale University Press. [https://mixtape.scunning.com/](https://mixtape.scunning.com/)
 
+## Citing diff-diff
+
+If you use diff-diff in your research, please cite it:
+
+```bibtex
+@software{diff_diff,
+  title = {diff-diff: Difference-in-Differences Causal Inference for Python},
+  author = {{diff-diff contributors}},
+  url = {https://github.com/igerber/diff-diff},
+  license = {MIT},
+}
+```
+
+See [`CITATION.cff`](CITATION.cff) for the full citation metadata.
+
 ## License
 
 MIT License
diff --git a/TODO.md b/TODO.md
@@ -63,6 +63,7 @@ Deferred items from PR reviews that were not addressed before merge.
 | R comparison tests spawn separate `Rscript` per test (slow CI) | `tests/test_methodology_twfe.py:294` | #139 | Low |
 | CS R helpers hard-code `xformla = ~ 1`; no covariate-adjusted R benchmark for IRLS path | `tests/test_methodology_callaway.py` | #202 | Low |
 | Context-dependent doc snippets pass via blanket NameError; no standalone validation | `tests/test_doc_snippets.py`, `docs/api/visualization.rst`, `docs/python_comparison.rst`, `docs/r_comparison.rst` | #206 | Low |
+| ~1,460 `duplicate object description` Sphinx warnings — each class attribute is documented in both module API pages and autosummary stubs; fix by adding `:no-index:` to one location or restructuring API docs to avoid overlap | `docs/api/*.rst`, `docs/api/_autosummary/` | — | Low |
 
 ---
 

diff --git a/docs/_static/custom.css b/docs/_static/custom.css
@@ -26,11 +26,6 @@ table.docutils td, table.docutils th {
     font-weight: bold;
 }
 
-/* Method/function signature styling */
-.sig-name {
-    font-weight: bold;
-}
-
 /* Better parameter list styling */
 .field-list {
     margin-top: 1em;

diff --git a/docs/_templates/layout.html b/docs/_templates/layout.html
@@ -0,0 +1,21 @@
+{% extends "pydata_sphinx_theme/layout.html" %}
+{% block extrahead %}
+{{ super() }}
+<script type="application/ld+json">
+{
+  "@context": "https://schema.org",
+  "@type": "SoftwareApplication",
+  "name": "diff-diff",
+  "description": "Python library for Difference-in-Differences causal inference analysis with sklearn-like API",
+  "applicationCategory": "Scientific Software",
+  "operatingSystem": "Cross-platform",
+  "programmingLanguage": "Python",
+  "url": "https://diff-diff.readthedocs.io",
+  "downloadUrl": "https://pypi.org/project/diff-diff/",
+  "softwareVersion": "{{ release }}",
+  "license": "https://opensource.org/licenses/MIT",
+  "offers": {"@type": "Offer", "price": "0", "priceCurrency": "USD"},
+  "author": {"@type": "Organization", "name": "diff-diff contributors"}
+}
+</script>
+{% endblock %}
diff --git a/docs/benchmarks.rst b/docs/benchmarks.rst
@@ -1,3 +1,7 @@
+.. meta::
+   :description: Validation benchmarks comparing diff-diff against R packages (did, synthdid, fixest). Coefficient accuracy, standard error comparison, and performance metrics.
+   :keywords: difference-in-differences benchmark, DiD validation R, python econometrics accuracy, did package comparison
+
 Benchmarks: Validation Against R Packages
 =========================================
 

diff --git a/docs/choosing_estimator.rst b/docs/choosing_estimator.rst
@@ -1,3 +1,7 @@
+.. meta::
+   :description: Guide to choosing the right Difference-in-Differences estimator. Covers basic DiD, TWFE, staggered adoption methods (Callaway-Sant'Anna, Sun-Abraham), Synthetic DiD, and more.
+   :keywords: which DiD estimator, staggered DiD estimator, difference-in-differences method selection, TWFE alternatives
+
 Choosing an Estimator
 =====================
 

diff --git a/docs/conf.py b/docs/conf.py
@@ -8,9 +8,6 @@
 
 # Add repository root to sys.path so autodoc imports from checked-out source
 # without needing pip install (which would require the Rust/maturin toolchain).
-# Note: visualization.py lazily imports matplotlib inside functions, so it is
-# not needed as a build dependency. If a future module adds a top-level
-# matplotlib import, add it to the RTD dep list in .readthedocs.yaml.
 sys.path.insert(0, os.path.abspath(".."))
 
 import diff_diff
@@ -30,10 +27,13 @@
     "sphinx.ext.viewcode",
     "sphinx.ext.intersphinx",
     "sphinx.ext.mathjax",
+    "sphinxext.opengraph",
+    "sphinx_sitemap",
+    "nbsphinx",
 ]
 
 templates_path = ["_templates"]
-exclude_patterns = ["_build", "Thumbs.db", ".DS_Store"]
+exclude_patterns = ["_build", "Thumbs.db", ".DS_Store", "llms.txt", "llms-full.txt"]
 
 # -- Options for autodoc -----------------------------------------------------
 autodoc_default_options = {
@@ -62,17 +62,56 @@
 napoleon_attr_annotations = True
 
 # -- Options for HTML output -------------------------------------------------
-html_theme = "sphinx_rtd_theme"
+html_theme = "pydata_sphinx_theme"
 html_static_path = ["_static"]
+html_title = "diff-diff: Difference-in-Differences Causal Inference for Python"
+# Use RTD's canonical URL when available; fall back to stable for local builds.
+_canonical_url = os.environ.get(
+    "READTHEDOCS_CANONICAL_URL",
+    "https://diff-diff.readthedocs.io/en/stable/",
+)
+html_baseurl = _canonical_url
+html_extra_path = ["llms.txt", "llms-full.txt"]
+sitemap_url_scheme = "{link}"
 
 html_theme_options = {
+    "icon_links": [
+        {
+            "name": "GitHub",
+            "url": "https://github.com/igerber/diff-diff",
+            "icon": "fa-brands fa-github",
+        },
+        {
+            "name": "PyPI",
+            "url": "https://pypi.org/project/diff-diff/",
+            "icon": "fa-brands fa-python",
+        },
+    ],
     "navigation_depth": 4,
-    "collapse_navigation": False,
-    "sticky_navigation": True,
-    "includehidden": True,
-    "titles_only": False,
+    "show_toc_level": 2,
+    "use_edit_page_button": True,
 }
 
+html_context = {
+    "github_user": "igerber",
+    "github_repo": "diff-diff",
+    "github_version": "main",
+    "doc_path": "docs",
+}
+
+# -- Options for sphinxext-opengraph -----------------------------------------
+ogp_site_url = _canonical_url
+ogp_site_name = "diff-diff"
+ogp_description_length = 200
+ogp_type = "website"
+ogp_enable_meta_description = True
+ogp_social_cards = {
+    "line_color": "#1f77b4",
+}
+
+# -- Options for nbsphinx ---------------------------------------------------
+nbsphinx_execute = "never"
+
 # -- Options for intersphinx -------------------------------------------------
 intersphinx_mapping = {
     "python": ("https://docs.python.org/3", None),
@@ -83,19 +122,17 @@
 
 # -- ReadTheDocs version-aware banner ----------------------------------------
 # Shows a warning on development builds so users know they may be reading
-# docs for unreleased features. Only activates on RTD (not local builds).
+# docs for unreleased features. Uses PyData theme's announcement bar on RTD,
+# falls back to rst_prolog for local builds.
 rtd_version = os.environ.get("READTHEDOCS_VERSION", "")
 rtd_version_type = os.environ.get("READTHEDOCS_VERSION_TYPE", "")
 
 if rtd_version == "latest" or rtd_version_type == "branch":
-    rst_prolog = """
-.. warning::
-
-   This documentation is for the **development version** of diff-diff.
-   It may describe features not yet available in the latest PyPI release.
-   For stable documentation, use the version selector (bottom-left) to switch to **stable**.
-
-"""
+    html_theme_options["announcement"] = (
+        "This documentation is for the <strong>development version</strong> of diff-diff. "
+        "It may describe features not yet available in the latest PyPI release. "
+        'Use the version selector to switch to <a href="/en/stable/">stable</a>.'
+    )
 
 # -- Custom CSS --------------------------------------------------------------
 def setup(app):

diff --git a/docs/index.rst b/docs/index.rst
@@ -1,3 +1,7 @@
+.. meta::
+   :description: diff-diff — Python library for Difference-in-Differences causal inference. Callaway-Sant'Anna, Synthetic DiD, Honest DiD, event studies, parallel trends. sklearn-like API, validated against R.
+   :keywords: difference-in-differences, python, causal inference, DiD, econometrics, treatment effects, staggered adoption, event study
+
 diff-diff: Difference-in-Differences in Python
 ==============================================
 
@@ -67,6 +71,84 @@ Quick Links
 
    api/index
 
+.. toctree::
+   :maxdepth: 1
+   :caption: Tutorials
+   :hidden:
+
+   tutorials/01_basic_did
+   tutorials/02_staggered_did
+   tutorials/03_synthetic_did
+   tutorials/04_parallel_trends
+   tutorials/05_honest_did
+   tutorials/06_power_analysis
+   tutorials/07_pretrends_power
+   tutorials/08_triple_diff
+   tutorials/09_real_world_examples
+   tutorials/10_trop
+   tutorials/11_imputation_did
+   tutorials/12_two_stage_did
+   tutorials/13_stacked_did
+   tutorials/14_continuous_did
+   tutorials/15_efficient_did
+
+What is Difference-in-Differences?
+----------------------------------
+
+Difference-in-Differences (DiD) is a quasi-experimental research design that estimates
+causal treatment effects by comparing outcome changes over time between treated and
+control groups. It is one of the most widely used methods in applied economics,
+public policy evaluation, and social science research.
+
+Why diff-diff?
+--------------
+
+- **Complete method coverage**: 13+ estimators from basic 2x2 DiD to cutting-edge methods like Efficient DiD (Chen et al. 2025) and TROP (Athey et al. 2025)
+- **Familiar API**: sklearn-like ``fit()`` interface — if you know scikit-learn, you know diff-diff
+- **Modern staggered methods**: Callaway-Sant'Anna, Sun-Abraham, Imputation DiD, Two-Stage DiD, and Stacked DiD handle heterogeneous treatment timing correctly
+- **Robust inference**: Heteroskedasticity-robust, cluster-robust, wild cluster bootstrap, and multiplier bootstrap
+- **Sensitivity analysis**: Honest DiD (Rambachan & Roth 2023) for robust inference under parallel trends violations
+- **Validated against R**: Benchmarked against ``did``, ``synthdid``, and ``fixest`` — see :doc:`benchmarks`
+- **No heavy dependencies**: Only numpy, pandas, and scipy
+
+Supported Estimators
+--------------------
+
+.. list-table::
+   :header-rows: 1
+   :widths: 30 70
+
+   * - Estimator
+     - Description
+   * - :class:`~diff_diff.DifferenceInDifferences`
+     - Basic 2x2 DiD with robust/clustered standard errors
+   * - :class:`~diff_diff.TwoWayFixedEffects`
+     - Panel data with unit and time fixed effects
+   * - :class:`~diff_diff.MultiPeriodDiD`
+     - Event study with period-specific treatment effects
+   * - :class:`~diff_diff.CallawaySantAnna`
+     - Callaway & Sant'Anna (2021) for staggered adoption
+   * - :class:`~diff_diff.SunAbraham`
+     - Sun & Abraham (2021) interaction-weighted estimator
+   * - :class:`~diff_diff.ImputationDiD`
+     - Borusyak, Jaravel & Spiess (2024) imputation estimator
+   * - :class:`~diff_diff.TwoStageDiD`
+     - Gardner (2022) two-stage residualized estimator
+   * - :class:`~diff_diff.SyntheticDiD`
+     - Synthetic DiD combining DiD and synthetic control
+   * - :class:`~diff_diff.StackedDiD`
+     - Wing, Freedman & Hollingsworth (2024) stacked DiD
+   * - :class:`~diff_diff.EfficientDiD`
+     - Chen, Sant'Anna & Xie (2025) efficient DiD
+   * - :class:`~diff_diff.TripleDifference`
+     - Triple difference (DDD) estimator
+   * - :class:`~diff_diff.ContinuousDiD`
+     - Continuous treatment DiD
+   * - :class:`~diff_diff.TROP`
+     - Triply Robust Panel with factor model adjustment (Athey et al. 2025)
+   * - :class:`~diff_diff.BaconDecomposition`
+     - Goodman-Bacon decomposition diagnostics
+
 Indices and tables
 ------------------