Projection: number, trend and verification

Содержание и основные понятия

01
The forecast doesn't change the unknown.
What there is.
Time observations: date, value, units and context of change.
What to Choose
Model and horizon: How many periods forward are allowed to estimate.
Assess the trend at historical points, then test the model for a period she didn't see. If the mistake is big, don't hide it behind a smooth line.
02
Mini-check
Δ
Linear assessment
If the monthly expenditure was reduced by about 12 units and in the last month there were 180, the next month's estimate is 168. But this does not work automatically for repairs, tariff changes or new equipment.
03
How to Check Forecasts
Phase
Action
Error We Catch
Separation
We're learning from the past, we're checking at a later stage.
looking to the future
Baseline
Compare it to the last or medium value.
A complicated model is worse than a simple rule.
Meteric
We're thinking of MAE and we're looking at individual failures.
average hides rare big mistakes
Scenario
We change the key parameter in the tolerance range.
Fragility of results
The projection is accompanied by a period of uncertainty and a description of the conditions under which it is no longer applicable.