Add Class for Repeated Cross-Sectional Data

[SvenKlaassen]

Adds a analog to DoubleMLDIDMulti for repeated cross-sectional data.

The changes include:

• [x] make_did_cs_CS2021 data generator
• [x] DoubleMLDIDCSBinary class
• [x] Update DoubleMLDIDMulti class to support repeated cross-sections
• [x] Updated plot_effects() method to color anticipation periods
• [x] Added gt_combinations="universal" option to DoubleMLDIDMulti

Further, generalize the __str__ method in the DoubleML class to allow for flexible output, e.g. see DoubleMLBinary.

Reference to Issues or PRs

See #317 Universal option #339

Comments

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[SvenKlaassen]

@PhilippBach Maybe you can check specifically the argument naming. Further, I have updated plot_effects() to highlight anticipation periods.