When you edit or replace data, Prism automatically recomputes all linked analyses. If you don't want a particular results sheet to automatically update when the data are changed, click the freeze button in the Sheet section of the toolbar.
For example, you might want to freeze the results before excluding some outliers from the data, then repeat the analysis and have both copies of the results in the project. Click again to unfreeze. When a sheet is frozen, you'll see the word "frozen" in the status bar at the bottom of the window, as well as a floating note that explains.
Note the distinction between deleting a data table and deleting all the values. If you erase all values from a data set using the DEL key, Prism still maintains the links between the data and the results. Since there are no data, the results become blank. If you delete the entire data table, the results remain and the sheet becomes orphaned.
Prism hot links data to analysis results. If you change the data, Prism will automatically recalculate the analyses and update the results. It will also update any result tables that have been embedded onto graphs, or any result values that have been hooked to dialogs.
If you delete a data table, any linked results become orphaned, and you'll see the word 'orphaned' in the bar at the bottom of the Prism window. When the data table is gone you can view and graph the orphaned results, but you cannot change the analysis parameters.