Forecast Seasonality

Refer, if this can help

https://powerbi.microsoft.com/pt-br/blog/introducing-new-forecasting-capabilities-in-power-view-for-office-365/

Hi datanau001 ,

The Seasonality in forecast means the number of points in a recurring seasonal pattern.

So in my opinion, since your sample data has 12 months, when you set seasonality as 12 points, it will show the forecast results depending on this. When you set seasonality as other points below 12, it will show a range result.

For further information about forecast, you can refer the following Microsoft blogs and cases that could help you:

1. https://community.powerbi.com/t5/Desktop/Forecasting-12-month-rolling-totals/td-p/605110
2. https://community.powerbi.com/t5/Desktop/Forecast-Functionality-in-PowerBI/td-p/124766
3. https://community.powerbi.com/t5/Desktop/Forecasting-in-Power-BI-The-Theory/td-p/365736
4. https://powerbi.microsoft.com/en-us/blog/introducing-new-forecasting-capabilities-in-power-view-for-office-365/

Best Regards,

Yingjie Li

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