Seasonal indices help you uncover repeating patterns in your data — whether it’s sales, web traffic, or demand. Here’s how to calculate them step by step:
Collect at least 3–5 years of data for the same period (e.g., monthly or quarterly). how to find seasonal index
📌 Example: If January’s average sales are 120 and the overall monthly average is 100, the seasonal index = 1.2 (20% above average). Seasonal indices help you uncover repeating patterns in
Here’s a clear, professional post you can use for LinkedIn, a blog, or a social media update: average of all Januaries).
Calculate the grand mean of all data points across all periods.
Find the average value for each season (e.g., average of all Januaries).