I have several surveys with its results and I would like to do one report and sum up all the results. Is it possible to do that in SharePoint?
As OOTB, there is no way to generate a report for multiple survey lists!
- For each list, Export the Survey result to a spreadsheet.
- Merge the result in one excel file
- Perform the calculation that you need!
Graphical SummaryView (Lists/Survey/summary.aspx) in the Survey List doesn't have Export to Spreadsheet option!!! Check how to export the result to excel at How to export survey results to excel