Thank you so much for your care - really appreciated!
We already had a hard fight 
on that issue, I gave in that time… https://discuss.tryton.org/t/usage-of-stock-supply-forecast/5036
Now I’m trying over again. So what I’m doing (already got quite some help from fellow @timitos):
- create a test case with sales of 100 pcs at Mar20, Apr15 and Jun15 2022.
- open menu > Inv&Stock > stock forecast
- create new forecast (ctrl-N)
- location: my own warehouse
- destination: customer
- window opens, type in from-to date: prognosis period (in the future)
- hit “complete forecast”
- type in from-to date: basis (comparison) period of time (in the past)
hit “choose product”, select one from list - hit “complete”
What happens: As a result I always get the number of items sold in the basis period, it does not make any difference how long the prognosis period is - and it does not matter how long the basis period is.
What I’d expect:
- result depends on the basis period: When I choose (in my above example) Mar19 to Mar21 I have 100pcs in 3 days - so ~12.000 per year. When I choose Jan1 to Mar21, I have 100pcs in ~80days, that’s only ~450 per year.
- prognosis period should matter: When I choose 1 month, I should get consumption per year / 12. When I choose 5 months, I should get consumption per year * 5 / 12.
I’m still not sure whether I expect wrong things from this module - and whether I’m using it on the wrong way.
Under products > suppliers > supplier I set 1M as “lead time”, but I don’t know how that affect the prognosis.
Cheers,
Wolf