The most common cause of the "Insufficient Data" error is either trying to use text X, Y, or Z values, or using a data file where the numbers are formatted as text instead of numeric values. To rectify this, you can:
- Open the file in the Surfer worksheet.
- Highlight the column of numeric data that is formatted as text (you can tell this if the numbers are left justified in the cells).
- Click Data | Data | Text to Number.
- Save the updated data file.