Module 05 Summary

What this module established

The time interval determines which variation is visible - the weekly cycle disappears entirely under weekly aggregation. Choose it from the decision, not from how the data arrives.

Carry forward

• Compare the same period year on year for seasonal data. Consecutive-period comparisons measure the season and change their story every month.
• Smoothing trades noise for lag and lost endpoints. Do not use a smoothed series for anything time-critical.
• Index when growth is the question, label the base period, and give the absolute values somewhere. Indexing hides magnitude entirely.

Before moving on

Move on when your seasonal comparisons are year-on-year and every forecast shows its interval.

Mark complete