user: Question: Which Date has a Margin of victory of 4 strokes?
Columns: ['Date', 'Tournament', 'Winning score', 'Margin of victory', 'Runner(s)-up']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['16 Sep 1984', 'World Seniors Invitational', '−7 (69-69-69-74=281)', '1 stroke', 'Arnold Palmer']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Margin of victory" = '4 strokes';