Can I expand the data file using drag-and-drop?

Yes. You can use drag-and-drop operations to increase the size of the spreadsheet by moving or copying a block [either all or some of the variable(s) or case(s)] beyond the current spreadsheet boundaries.

You can also expand the spreadsheet using the Insert operation (see What are the drag-and-drop facilities?). This operation inserts the block between cases or variables, thereby increasing the size of the spreadsheet. Note that whether you move, copy, or insert new cases or variables, when the block contains only part of a variable or case, then STATISTICA fills the remaining values in the variable/case with missing data.