user: Question: When was incumbent Leo E. Allen first elected?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Illinois 4', 'Harry P. Beam', 'Democratic', 1930.0, 'Re-elected', 'Harry P. Beam (D) 80.8% Irene A. Tomas (R) 19.2%']
SQL:

assistant: SELECT "First elected" FROM "Table" WHERE "Incumbent" = 'Leo E. Allen';