CREATE TABLE table_23811 ("Date of opinion poll" CLOB, "Conductor" CLOB, "Sample size" FLOAT, "For" CLOB, "Against" CLOB, "Undecided" CLOB)

When was Quantum Research's poll conducted?
SELECT "Date of opinion poll" FROM table_23811 WHERE "Conductor" = 'Quantum Research'
SELECT "Date of opinion poll" FROM "table_23811" WHERE "Conductor" = 'Quantum Research'