user: Question: What is the first electedfor district Ohio 18
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Ohio 2', 'William E. Hess', 'Republican', 1938.0, 'Re-elected', 'William E. Hess (R) 56.0% J. Harry Moore (D) 44.0%']
SQL:

assistant: SELECT "First elected" FROM "Table" WHERE "District" = 'Ohio 18';