Doubleml

- **Release highlight:** Benchmarking for Sensitivity Analysis (omitted variable bias) [211](https://github.com/DoubleML/doubleml-for-py/pull/211)

- Policy tree estimation for the `DoubleMLIRM` class [212](https://github.com/DoubleML/doubleml-for-py/pull/212)

- Extending sensitivity and policy tree documentation in User Guide and Example Gallery [148](https://github.com/DoubleML/doubleml-docs/pull/148) [#150](https://github.com/DoubleML/doubleml-docs/pull/150)

- The package requirements are set to Python 3.8 or higher [211](https://github.com/DoubleML/doubleml-for-py/pull/211)

- Maintenance documentation [149](https://github.com/DoubleML/doubleml-docs/pull/149)

- Maintenance package [213](https://github.com/DoubleML/doubleml-for-py/pull/213)

- Fix install requirements for 0.6.2 [208](https://github.com/DoubleML/doubleml-for-py/pull/208)

- **Release highlight:** Sensitivity Analysis (omitted variable bias) for [201](https://github.com/DoubleML/doubleml-for-py/pull/201)

- `DoubleMLPLR`
- `DoubleMLIRM`
- `DoubleMLDID`
- `DoubleMLDIDCS`

- Updated documentation [144](https://github.com/DoubleML/doubleml-docs/pull/144) [#141](https://github.com/DoubleML/doubleml-docs/pull/141)

- Extend the guide with sensitivity and add further examples [142](https://github.com/DoubleML/doubleml-docs/pull/142)

- Maintenance package [202](https://github.com/DoubleML/doubleml-for-py/pull/202) [#206](https://github.com/DoubleML/doubleml-for-py/pull/206)

- Maintenance documentation [137](https://github.com/DoubleML/doubleml-docs/pull/137) [#138](https://github.com/DoubleML/doubleml-docs/pull/138) [#140](https://github.com/DoubleML/doubleml-docs/pull/140) [#143](https://github.com/DoubleML/doubleml-docs/pull/143) [#145](https://github.com/DoubleML/doubleml-docs/pull/145) [#146](https://github.com/DoubleML/doubleml-docs/pull/146)

- **Release highlight:** Difference-in-differences models for ATTE estimation [200](https://github.com/DoubleML/doubleml-for-py/pull/200) [#194](https://github.com/DoubleML/doubleml-for-py/issues/194)
- Panel data `DoubleMLDID`
- Repeated cross sections `DoubleMLDIDCS`

- Add a potential time variable to `DoubleMLData` (until now only used in `DoubleMLDIDCS`) [200](https://github.com/DoubleML/doubleml-for-py/pull/200)

- Extend the guide in the documentation and add further examples [132](https://github.com/DoubleML/doubleml-docs/pull/132) [#133](https://github.com/DoubleML/doubleml-docs/pull/133) [#135](https://github.com/DoubleML/doubleml-docs/pull/135)

- Maintenance [199](https://github.com/DoubleML/doubleml-for-py/pull/199) [#134](https://github.com/DoubleML/doubleml-docs/pull/134) [#136](https://github.com/DoubleML/doubleml-docs/pull/136)

- **Release highlight:** Heterogeneous treatment effects (GATE, CATE, Quantile effects, ...)
- Add out-of-sample RMSE and targets for nuisance elements and implement nuisance estimation
evaluation via `evaluate_learners()`. [182](https://github.com/DoubleML/doubleml-for-py/pull/182) [#188](https://github.com/DoubleML/doubleml-for-py/pull/188)
- Implement `gate()` and `cate()` methods for `DoubleMLIRM` class. Both are
based on the new `DoubleMLBLP` class. [169](https://github.com/DoubleML/doubleml-for-py/pull/169)
- Implement different type of quantile models [179](https://github.com/DoubleML/doubleml-for-py/pull/179)

- Potential quantiles (PQ) in class `DoubleMLPQ`
- Local potential quantiles (LPQ) in class `DoubleMLLPQ`
- Conditional value at risk (CVaR) in class `DoubleMLCVAR`
- Quantile treatment effects (QTE) in class `DoubleMLQTE`

- Extend clustering to nonlinear scores [190](https://github.com/DoubleML/doubleml-for-py/pull/190)
- Add `ipw_normalization` option to `DoubleMLIRM` and `DoubleMLIIVM` [186](https://github.com/DoubleML/doubleml-for-py/pull/186)
- Implement an abstract base class for data backends [173](https://github.com/DoubleML/doubleml-for-py/pull/173)
- Code refactorings, bug fixes, docu updates, unit test extensions and continuous integration [183](https://github.com/DoubleML/doubleml-for-py/pull/183) [#192](https://github.com/DoubleML/doubleml-for-py/pull/192) [#195](https://github.com/DoubleML/doubleml-for-py/pull/195) [#196](https://github.com/DoubleML/doubleml-for-py/pull/196)
- Change License to BSD 3-Clause [198](https://github.com/DoubleML/doubleml-for-py/pull/198)
- Maintenance [174](https://github.com/DoubleML/doubleml-for-py/pull/174) [#178](https://github.com/DoubleML/doubleml-for-py/pull/178) [#181](https://github.com/DoubleML/doubleml-for-py/pull/181)

- Add documentation for estimated models for nuisance parameters [181](https://github.com/DoubleML/doubleml-for-r/pull/181)
- New contributor SvenKlaassen
- Maintenance [179](https://github.com/DoubleML/doubleml-for-r/pull/179)