cff-version: 1.2.0
message: "If you use this software, please cite both the software and the paper."
type: software
title: "lwdid: Difference-in-Differences Estimator for Small Cross-Sectional Samples"
version: 0.1.0
date-released: 2025-11-25
authors:
  - family-names: Cai
    given-names: Xuanyu
    email: F23090105414@cityu.edu.mo
    affiliation: City University of Macau
    orcid: https://orcid.org/0009-0003-0980-8081
  - family-names: Xu
    given-names: Wenli
    email: wlxu@cityu.edu.mo
    affiliation: City University of Macau
repository-code: "https://github.com/gorgeousfish/lwdid-py"
url: "https://lwdid.readthedocs.io"
abstract: >
  Python implementation of the Lee & Wooldridge (2025) 
  difference-in-differences estimator for small cross-sectional 
  samples. Supports unit-specific demeaning and detrending 
  transformations, quarterly data with seasonal effects, 
  time-invariant controls, and randomization inference.
keywords:
  - difference-in-differences
  - causal inference
  - econometrics
  - panel data
  - small samples
  - Python
license: AGPL-3.0-or-later
preferred-citation:
  type: article
  title: "Simple Approaches to Inference with Difference-in-Differences Estimators with Small Cross-Sectional Sample Sizes"
  authors:
    - family-names: Lee
      given-names: Soo Jeong
    - family-names: Wooldridge
      given-names: Jeffrey M.
  journal: ""
  year: 2025
  status: submitted
  notes: "Available at [SSRN 5325686](https://papers.ssrn.com/sol3/papers.cfm?abstract_id=5325686). Please cite this paper when using the software."
