Seasonality !!top!! — Calculating

: Python + statsmodels Best no-code : Excel or Tableau

Here is a conceptual snippet of how decomposition is handled programmatically: calculating seasonality

If the average ratio for December is 1.25, your December Seasonal Index is 125. This means December sales are typically 25% higher than the average month. : Python + statsmodels Best no-code : Excel

Note: This method is less accurate if you have a strong upward or downward trend, as the later years will skew the averages. like months or quarters.

Break your data into consistent time chunks, like months or quarters.