Reference dates for net worth barchart

[Geert Janssens]

On Saturday 07 November 2015 02:00:30 Wm... wrote:
> Thu, 5 Nov 2015 18:26:22 <1883999.Jh6Ha8s1L7 at legolas.kobaltwit.lan>
> Geert Janssens <geert.gnucash at kobaltwit.be> wrote...
> 
> >The part of the patch I'm interested in here now is the part where
> >you changed code to unconditionally use the start-day-time for the
> >from-date, where it was using either start-day- time or end-day-time
> >depending on whether the report is for income/expense or not. Your
> >patch may be correct, but I don't know because I have no idea why
> >this distinction was there in the first place. I would like to hear
> >if other users/devs know this before I apply your patch.
> 
> To state the obvious:
> 
> Asset, Liability and Equity accounts are usually reported on at a
> point in time (nominally a moment before midnight, I don't think we
> need to involve time zones here).
> 
> Income and Expense accounts are usually reported on over a period in
> time, nominally moment after midnight to moment before midnight.
> 
> The Net Worth Barchart is (or should be) balance sheet type reporting,
> in plain terms the sum of a set of accounts (or a single balance
> sheet account) of the users choice at a point in time.  And some
> other point in time.  And another one.  And so on.  But, to be clear,
> points in time for Balance Sheet accounts represented by a bar on a
> chart.
> 
> If my argument holds true the table that goes along with the Net Worth
> Barchart will match balance sheets produced for the same time.
> 
> Time passes, I've done some spot checks on weekly data from accounts
> I'm familiar with that change at least weekly and it holds true.
> 
> Does the graph match the table?  To test this I hovered my cursor over
> bars in the chart and checked if they matched (date and amount) with
> the table.  Answer: yes, they match.
> 
> I'm not seeing a reason for change in terms of what is displayed.

Very insightful. Thanks Wm. And very obvious from an accounting perspective. It just didn't 
occur to me with my head in coding mode :(

With the above in mind I agree the report's behavior shouldn't be changed in this context.
> 
> >  So does anyone know a good reason to use another start time for
> >
> >income-expense reporting vs other reports ?
> 
> Ummm, if the report was about a period of time (Income Statement or
> Profit and Loss type reports) rather than a point in time then this
> might be something to discuss.  As far as I can tell the Net Worth
> Barchart is a series of Balance Sheet reports.
> 
> >It has been like this since 2001 at least when the report was first
> >introduced as a merger between "income-expense-graph.scm" and
> >"net-worth-timeseries.scm" [3] by Christian Stimming. The former used
> >day-start-time, the latter used day-end-time.
> 
> Before my time but if appropriate moments are picked there needn't be
> a problem per se.
> 
> ===
> 
> Having said all that I'm wondering what the issue for JD is.  I think
> (but may be wrong) that his moan is about arbitrary human *time
> periods* not always matching up.
> 
> We should all know that weeks, months and years can be weird if you
> are dumb enough to believe in a god or follow a particular government
> and prefer their definition of time versus one other humans
> understand.
> 
> Locally, if I use "Step size: week" I get 7 days per step.
> 
> Locally if I use "Step size: month" I get a varying number of days.
> 
This is the core issue described in the bug David Carlson was referring at [1]. It's unrelated 
to the patch JD proposed IMO.

Regards,

Geert

[1] https://bugzilla.gnome.org/show_bug.cgi?id=639049