The image you uploaded contains a partial table with the following columns:

• Year
• Seq No.
• Month
• Widget Sales Volume
• Smoothed Level
• Forecast for Next Period
• Forecast Error
• Squared Error

To populate the rest of the table and calculate the Sum of Squared Errors (SSE), we need to proceed with these steps:

1. Use an appropriate forecasting method (e.g., simple exponential smoothing) to calculate the smoothed level and forecast for each period.
2. Calculate the forecast error for each period by subtracting the forecast from the actual widget sales volume.
3. Square the forecast errors to get the squared errors.
4. Sum the squared errors to get the SSE.

Since the table contains a few values, I need to know which forecasting method is used (e.g., simple exponential smoothing with a given smoothing constant or another approach). Could you confirm the forecasting method or provide more details?