fix time bounds in daily and monthly statistics

[SarahAlidoost]

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Closes #398

[valeriupredoi]

nice one! can you please add a note in the docstrings and in the documentation about this, it's useful for users to know what they get out of this 😁

[SarahAlidoost]

nice one! can you please add a note in the docstrings and in the documentation about this, it's useful for users to know what they get out of this

The notes are added.

[valeriupredoi]

great, cheers @SarahAlidoost 🍺

[bouweandela]

I'm not really convinced that this is the right approach. The computed time points do correspond to the average of the input time points used to compute the statistic, e.g. to get the daily statistic, data from time points 0...23 hour is used, resulting in 11.5 hour as the average time point. See also the discussion in #398

[mattiarighi]

@SarahAlidoost do you want to update this given @bouweandela's comment above?

[bouweandela]

Closing this pull request for now. Let's first continue the discussion in the issue and then a new pull request can be opened if needed.